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CALIFORNIA   STATE   MINING   BUREAU 

FERRY  BUILDING,  SAN   FRANCISCO 
FLETCHER  HAMILTON  State  Mineralogist 


San  Francisco]  BULLETIN  No.  89  [July,  1921 


PETROLEUM  RESOURCES 
OE  CALIEORNIA 


With  Special  Reference  to  Unproved  Areas 


BY 

LAWRENCE  VANDER  LECK 


CiJ.IFORNIA   STATE  PRINTING  OFFICE 
SACRAMENTO 


13322 


TABLE  OF  CONTENTS. 


Chapter  I. 


Paaes 


GENERAL  THEORY  OF  THE  ORIGIN  AND  ACCUMULATION  OF  OIL  IN 
CALIFORNIA. 
Organic  theory  of  origin.  Organic  shales.  Migration  and  accumulation. 
Theories  as  to  accumulation.  Reservoirs.  Saturation  and  recovery.  Areas 
of  accumulation.  Summary  of  the  conditions  necessary  for  the  accumulation 
of  oil  in  commercial  quantities  in  California.     Surface  indications  of  oil 13-22 

Chapter  II. 

DESCRIPTION  OF  THE  OIL  BEARING  FORMATIONS  IN  CALIFORNIA. 
General  geology  and  structure  of  the  State.  Coast  Ranges.  Great  Central 
"Valley.  Lava  beds  of  the  nortliwest  region.  Sierra  Nevada.  Southwest 
Desert  Region.  Faults.  Non-oil  bearing  formations.  Oil  bearing  formations. 
Cretaceous  Eocene.  Oligocene.  Miocene.  Pliocene.  Description  of  correla- 
tion table . 23-34 

Chapter  III. 

POSSIBILITIES  OF  OIL  IN  THE  COAST  AREA  NORTH  OF  THE  BAY 
OP  SAN  FRANCSCO, 

(Includes  the  counties  of  Marin,  Sonoma,  Mendocino,  Humboldt,  Del  Norte 
and  Trinity.)  Marin  County.  Point  Reyes  peninsula.  Bolinas.  Sonoma 
County.  Wells  on  the  Ducker  Rancli.  Mendocino  County.  General  Geology. 
Point  Arena  District.  Humboldt  County.  General  Geology.  District  of  the 
Mattole  River.  Wells  drilled.  Del  Norte  and  Trinity  counties.  General 
Geology — 35-44 

Chapter  IV. 

OIL  POSSIBILITIES  OF  NORTHWESTERN  CALIFORNIA. 

(Consists  of  the  counties  of  Siskiyou,  Modoc.  Shasta  and  Lassen.)  Descrip- 
tion of  the  geological  formations  and  oil  possibilities  of  Siskiyou,  Modoc,  Shasta 
and  Lassen  counties 45-47 

Chapter  V. 

AREA  OF  THE  SIERRA  NEVADA  MOUNTAINS. 

(Consists  of  the  following  counties:  Plumas,  Sierra,  eastern  part  of  Butte 
County,  eastern  part  of  Yuba  County,  Nevada,  eastern  part  of  Placer,  El 
Dorado,  Amador,  Alpine,  Calaveras,  Tuolumne,  Mariposa,  eastern  part  of 
Madera,  eastern  part  of  Fresno  and  Tulare  counties,  and  that  part  of  Kern 
County  that  lies  in  the  Sierras.)  Description  of  the  geology  and  oil  possi- 
bilities of  this  region 48 

Chapter  VI. 

AREA  OF  THE  SACRAMENTO  VALLEY,  INCLUDING  THE  EAST  SLOPE 
OF  THE  COAST  RANGES,  AND  THE  FOOTHILLS  OF  THE  SIERRA 
NEVADA. 

(Consists  of  the  counties  of  Tehama,  Glenn,  western  Butte,  Yuba,  Sutter, 
Colusa.  Lake,  Yolo,  Napa.  Solano,  western  Placer  and  Sacramento.)  West 
side  of  the  Valley  and  east  slope  of  the  Coast  ranges.  Topography.  Geology. 
Indications  of  petroleum.  Structure.  Oil  possibilities.  Wells  drilled.  District 
of  the  Valley  floor.  Hooker  Hills.  Marysville  Buttes.  Montezuma  Hills. 
Wells  drilled.  East  side  of  the  Valley  and  foothills  of  the  Sierra  Nevada. 
General  geology.     Tuscan   Springs 49-59 


CALIFORNIA   STATE    MINING   BUREAU. 


Chapter  VII. 


Pages 


AREA  OF  THE  CO.\ST  RANGES  FROM  SAN  FRANCISCO  BAY  AS  FAR 
SOUTH  AS  THE  PAJARO  RIVER. 
(Includes  the  counties  of  Contra  Costa,  Alameda,  San  Francisco,  San  Mateo, 
Santa  Clara  and  Santa  Cruz.)  Contra  Costa  County,  Mount  Diablo  area.  Seep- 
ages and  wells  drilled.  San  Pablo  Valley.  Geology.  Wells  drilled.  Arnold's 
report.  San  Francisco  County.  San  Mateo  County.  General  Geology. 
Seepages  and  wells  drilled  near  Half  Moon  Bay,  Santa  Clara  County.  General 
Geology.  Moody  Gulch,  Los  Gatos  District.  Sargent  Oil  Field.  Santa  Cruz 
County.     General  Geology.     Seepages  and  wells  drilled  north  of  Watsonville..       60-68 

Chapter  VIII. 

COAST  RANGES  FROM  THE  PA.IARO  RIVER  AS  FAR  SOUTH  AS  THE 
SANTA  M.ARI.V  RIVER. 
(Includes  the  counties  of  San  Benito,  Monterey  and  San  Luis  Obispo.)  San 
Benito  County,  area  around  HoUister.  Tres  Pinos.  San  Benito  and  Santa 
Ana  valleys.  Vallecitos  District.  Anderson  and  Pack's  report.  Southwestern 
portion  of  the  county.  Packs  and  English's  report  on  the  Bellerwater  and 
Peachtree  valleys.  Wells  drilled.  Monterey  County.  Mouth  of  the  Salinas 
Vall«y.  Santa  Lucia  Mountains.  Arroyo  Seco  District.  Seepages.  Gavilan 
Mountains.  Salinas  Valley  from  Salinas  to  Greenfield.  San  Antonio  Hills. 
Seepages.  Fleyto  District.  English's  report.  Salinas  Valley  from  Greenfield 
south  to  the  county  line.  Bradley  anticline.  Wells  drilled.  English's  report 
on  San  Ardo  District.  Area  east  of  the  Salinas  Valley.  Parkfleld  District. 
Pack  and  English's  report.  Wells  drilled.  San  Luis  Obispo  County.  General 
geology  of  northern  portion.  Arroyo  Grande  Oil  Field.  Huasna  District. 
Carrisa  Plains  and  San  Juan  Creek.      Arnold  and  Johnson's  report .,      69-101 

Chapter  IX. 

COAST  AREA  FROM  SANTA  MARIA  TO  THE  SANTA  MONICA  MOUN- 
TAINS. 
(Includes  the  counties  of  Santa  Barbara.  Ventura,  and  northwestern  Los 
Angeles.)  Santa  Barbara  County.  Topography.  Proven  fields  and  adjoining 
areas.  Casmalia  Field.  Santa  Maria  Field.  Cat  Canyon  Field.  Purisima 
Hills.  Lompoc  Field.  Santa  Ynez  and  San  Rafael  mountains.  Cuyama 
Valley.  English's  report.  Coast  area.  Summerland  and  Rincon  districts. 
Arnold's  report.  Ventura  County.  Northern  lialf  of  the  county.  Ojai  Valley 
fields.  Santa  Paula  Field.  Ventura  Field.  South  Mountain  and  Oak  Ridge. 
Montebello.  Bardsdale,  Sespe  Canyon.  Piru  Field.  Tony  and  Eureka  canyons. 
Simi  Valley.  Topo  Canyon.  Brea  Canyon.  Unproven  areas  in  the  Simi 
Valley.  Lower  end  of  Simi  Valley.  Santa  Monica  Mountains.  Conejo  Field, 
northwestern  Los  Angeles  County.      General  geology.      Newhall  District 102-130 

Chapter  X. 

SOUTHERN  LOS  ANGELES  AND  ORANGE  COUNTY. 

Santa  Monica  Mountains.  San  Fernando  Valley  Coastal  plane  of  Los 
Angeles  and  Orange  counties.  Lines  of  structure.  Proven  fields.  Salt  Lake. 
Los  Angeles  City.  Montebello.  Whittier,  Brea  Canyon  and  Olinda,  Richfield. 
Coyote  Hills.  Santa  Fe  Springs.  Newport.  Huntington  Beach.  Signal 
Hill.  Inglewood.  Beverly  Hills.  San  Pedro.  Redondo  District.  San  Gab- 
riel Valley.  Puente  Hills.  San  Jo.se  Hills.  Eastern  portion  of  Orange 
County.      Santa  .\na  Mountains.      Laguna  Hills  and  Capistrano  District 131-143 

CHAPTHai    XI. 

SAN  DIEGO  .\ND  IMPERIAL  COITNTIES. 

San  Diego  County.  General  geology  of  mountain  area.  Coastal  district. 
Geology  and  oil  possibilities  of  region  north  of  Del  Mar.  Wells  drilled. 
Geology  and  oil  po.ssibilities  of  region  south  of  Del  Mar.  Wells  drilled. 
Kerr's  report.  Imperial  County.  General  geology  and  oil  possibilities.  Kerr's 
report.     Wells  drilled 145-152 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  5 

Chapter  XII. 

THE  DESERT  REGION.  rag.s 

(Includes  the  counties  of  Riverside,  San  Bernardino,  northeastern  Los 
Angeles,  eastern  Kern,  Inyo  and  Mono.)  General  geology  and  topography 
of  this  region.  Mono  County.  Geology  and  wells  drilled  at  Mono 
Liike.  Eastern  Kern  County.  Mohave  Desert.  Antelope  Valley.  North- 
eastern Los  Angeles  County.  San  Bernardino  County.  Barstow-Kraemer 
region.  Pack's  report.  District  lying  west  of  San  Bernardino  Mountains. 
Chino  Hills.  Riverside  County.  General  geology.  Wells  drilled.  Oil  possi- 
bilities   -- '. 153-161 

Chapter  XIII. 

REGION  OF  THE  SAN  JOAQUIN  VALLEY. 

(Includes  the  counties  of  San  Joaquin,  Stanislaus,  Merced,  western  one- 
third  of  Madera,  the  western  two-thirds  of  Fresno,  Kings,  the  western  half 
of  Tulare  and  Kern.)  General  geology  of  the  Valley.  Structure,  buried 
structures.  Region  of  the  proven  tields.  Midway.  Sunset.  McKittrick.  Bel- 
ridge.  Ix)st  Hills.  Devils  Den.  Elk  Hills,  ("oalinga.  Kern  River.  Unproven 
areas.  Soutli  end  of  the  Valley.  Foothills  of  tlie  temblor.  Kettleman  Hills. 
Kreyenhagen  Hills.  Region  north  of  Coalinga.  Tulare  Lake.  Buttonwillow. 
East  side  of  the  Valley 163-179 


CALIFORNIA   STATE    MINING   BUREAU. 


FIGURES. 

Pa«e 

Frontispiece 8 

Fig.     1.  Different  Types  of  Structure  Common  to  the  Oil  Fields 15 

Fig.     2.  Methods    of    Accumulation    in    Various    Types    of    Structures    Found    in 

California   Fields -- 17 

Sec.  1 — East-west  section  across  the  Midway  District,  Kern  County, 
showing  accumulation  on  a  monocline,  syncline  and  anticline. 

Sec.  2 — Shows  accumulation  on  an  anticlinal  fold  in  the  Santa  Maria 
Field,   Santa  Barbara  County. 

Sec.  3 — North-south  section  across  Salt  Lake  Field,  Los  Angeles  County, 
showing  accumulation  along  a  fault  zone. 

Fig.    3.   East-west    section    across    the    Point    Reyes    Peninsula,    about    two    miles 

north  of  Bolinas,  Marin  County — 37 

Fig.    4.  East-west  sections  across  western  side  of  the  Sacramento  "Valley 53 

Fig.    5.   Section  up  Moody  Gulch,  Santa  Clara  County 65 

Fig.    6.   Sec.  A-B — East-west  section  across  the  San  Benito  and  Tres  Finos  valleys, 

through  town  of  Tres  Pinos,  San  Benito  County 70 

Sec.  C-D — North-south  'section  across  the  Vallecitos  District,  San  Benito 
County. 

Sec.  E-F — East-west  section  across  Lewis  Creek  and  the  Peachtree  Valley 
in  vicinity  of  Lonoak,   Monterey  County. 

Fig.    7.   Sec.  A-B — North-south  section  across  Sulphur  Mountain  and  Ojai  Valley, 

in  vicinity  of  Upper  Ojai  fields,  Ventura  County 114 

Sec.  C-D — North-south  section  across  the  Simi  Valley,  Ventura  County, 
in  the  vicinity  of  Simi. 

Fig.    8.  North-south  section  through  the  Conejo  Field,  Ventura  County 128 

P'ig.  9.  Sec.  A-B — Generalized  section  across  Coastal  plain  area  of  Orange  County, 
showing  three  general  lines  of  structure  along  which  oil  has 
accumulated -- 134 

Fig.   10.   Sec.  A-B — From    Laguna   to   Santa    Ana  Mountains,    across   the   Laguna 

Hills  and  the  Capistrano  Valley,  Orange  County 144 

Fig.   11.   Sec.   A-B — East-west   section    along   the    north    side   of    Santa   Margarita 

Valley,  San  Diego  County 147 

Sec.  C-D — East-west  section  through  La  Jolla,  San  Diego  County. 

Fig.   12.   Hypothetical  sections  across  San  Joaquin  Valley 165 

Sec.  A-B — Shows  possible  accumulation  in  region  north  of  Coalinga. 
Sec.   C-D — Shows   proven   fields    and   possible   accumulation   in   region    of 
Tulare  Lake. 


PHOTOGRAPHS. 


Elk  Hills  Field,  Kern  County 169 

Huntington  Beach  Field,  Orange  County 139 

Midway  Oil  Field,  Kern  County 175 

Montebello  Field,  Los  Angeles  County — 132 

Oak  Ridge  Anticline,  Ventura  County 112 

Richfield  Field,  Orange  County 137 


PLATES  IN  POCKET. 

Map  of  California. 

Correlation  table. 

Point  Arena. 

Humboldt  County. 

West  side  of  Sacramento  Valley. 

Imperial  County. 


Plate 

I. 

Plate 

II. 

Plate 

III. 

Plate 

IV. 

Plate 

V. 

Plate 

VL 

LETTER  OF  TRANSMITTAL. 

To  His  Excellency,  the  Honor^^ble  William  D.  Stephens, 
Governor  of  the  State  of  Calif arnia. 

Sir: — I  have  the  honor  to  herewith  transmit  Bulletin  No.  89  of  the 
State  Mining  Bureau,  relating  to  the  Petroleum  Resources  of  California. 

The  increasing  demand  for  petroleum  and  its  products,  and  the 
inability  of  production  to  keep  pace  with  requirements,  for  several  years, 
have  resulted  in  widespread  prospecting  throughout  the  world  for  pos- 
sible new  oil  fields.  In  California,  'wild-cat'  wells  are  being  drilled  in 
many  localities,  some  of  them  in  places  where  even  a  cursory  inspection 
of  the  geology  would  tell  of  the  futility  of  looking  for  oil.  For  this 
reason,  the  report  herein  aims  to  furnish  information  as  to  the  unfavor- 
able as  well  as  to  the  favorable  areas  for  development  of  additional 
petroleum  resources  in  California. 

Respectfully  submitted. 

Fletcher  Hamilton, 

State  Mineralogist. 
July  21,  1921. 


N 


CALIFORNIA  STATE  MINING  BUREAU- 
FLETCHER  HAMILTON- 
STATE  MINEBALOCIST 

OUTLINE  MAP 

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INTRODUCTION. 

Purpose  and   Extent  of  the   Report. 

The  purpose  of  tliis  report  is  to  briefly  take  stock  of  the  oil  resources 
of  the  state  and  in  particular  to  determine,  if  possible,  the  opportunity 
that  exists  for  extending  the  productive  area  into  districts  that  have 
hitherto  been  resrarded  as  unfavorable.  In  line  with  Ibis  policy  the 
greater  portion  of  the  writer's  time  was  spent  in  investigating  the 
so-ealled  unproven  areas,  particularly  in  th(^  northern  portion  of  the 
state. 

In  the  time  allotted  for  the  work  it  was  found  impossible  to  give  a 
detailed  description  of  any  one  area  and  it  is  oidy  intended  that  the 
report  .should  block  out  those  areas  which  nuiy  be  regarded  as  distinctly 
unfavorable  and  those  which  may  ])c  considered  as  worthy  of  further 
investigation.  AVliile  a  greater  leu'Oith  of  time  would  have  been  prefer- 
able it  was  recognized  that  briefness  was  essential,  if  the  report  was  to 
be  of  any  value  in  the  present  campaign  of  exploration.  A  total  of  six 
months  was  spent  in  field  work  and  a  distance  of  fifteen  thousand  miles 
was  covered.  A  second  six  months  was  spent  in  writing  the  report  and 
assembling  data.  Tn  a  portion  of  the  field  work  in  Northern  California, 
the  writei-  was  assisted  1)\-  ^Fr.  E.  Iluguenin,  engineer  of  the  Bureau. 

A  I)i-ief  description  only  has  been  given  of  the  ]n-ovcn  fields.  The 
possibility  of  their  extension  has  been  noted  in  a  general  way.  Readers 
who  are  interested  in  the  details  of  these  areas  are  referred  to  the 
numerous  publications  of  the  United  States  Geological  Survey  and  the 
State  ^Mining  Bureau,  a  list  of  these  being  included  in  the  report. 

Chapter  I  has  been  devoted  to  descril)ing  the  general  geological  facts 
that  govern  the  origin  and  accumulation  of  petroleum  in  California 
based  upon  the  actual  conditions  that  exist  in  the  proven  fields.  A 
knowledge  of  these  conditions  is  absolutely  necessary  for  successful 
exploration  work.  Chaptei'  II  describes  the  rock  formations  of  the  state 
which  are  directly,  or  indirectly,  connected  with  the  petroleum  deposits. 
The  character,  thickness,  where  found,  relationship  to  the  oil  measures 
and  relative  productiveness  are  briefly  discussed. 

The  general  principles'  laid  down  in  these  two  chapters  have  then 
been  applied  to  the  various  areas  wliicli  ai'e  described  in  the  remainder 
of  the  report.  In  determining  what  chapter  contains  the  description  of 
any  certain  district,  the  index  map  (fi'ontispiece)  showing  the  area 
covered  by  each,  will  be  found  heli)fnl. 


10  CALIFORNIA   STATE   MINING  BUREAU. 

Plate  I,  a  map  of  the  state,  showing  in  color  the  possibilities  of  the 
different  areas,  is  intended  only  as  a  generalized  summing  up  and  the 
reader  is  referred  to  the  text  for  the  exact  possibilities  of  the  different 
areas. 

Acknowledgments. 

In  the  preparation  of  the  report  tlie  writer  has  used  freely  all  publica- 
tions available  upon  the  subject.  Especially  have  the  reports  of  the 
United  States  Geological  Survey,  the  Bulletins  of  the  Department  of 
Geology  of  the  University  of  California  and  publications  of  the  State 
Mining  Bureau  been  used. 

To  various  members  of  the  staff  of  the  Bureau  the  writer  wishes  to 
acknowledge  his  thanks.  In  particular  to  Mr.  R.  E.  CoUom,  State  Oil 
and  Gas  Supervisor,  for  general  advice  on  the  report.  To  Mr.  Walter 
W.  Bradley,  Statistician,  for  assistance  in  preparing  the  manuscript, 
and  to  ]\Ir.  Emil  Huguenin;  engineer,  for  assistance  in  the  field  work  in 
Northern  California. 

To  Prof.  B.  L.  Clark  of  the  University  of  California  the  writer  is 
indebted  for  assistance  in  preparing  the  correlation  table  of  the  oil- 
bearing  formations. 

To  the  following,  acknowledgement  is  due  for  information  regarding 
the  various  areas:  Mr.  C.  L.  Decius,  geologist  of  the  Pacific  Oil  Com- 
pany; Mv.  F.  Tickell,  geologist  of  the  Southern  Pacific  Company;  Mr. 
R.  N.  Ferguson,  petroleum  geologist  of  Bakersfield;  ]\Ir.  C.  C.  Thoms, 
deputy  supervisor  of  the  Department  of  Oil  and  Gas,  Taft;  ]\rr.  Tom 
O'Neal  of  Pt.  Arena;  Mr.  R.  C.  McDonald,  engineer  of  "Williams;  Mr. 
Don  McKinney  of  Esparto ;  Mr.  W.  E.  Schumacher  of  the  Standard  Oil 
Company ;  ]\Ir.  A.  Folger,  geologist  of  the  Standard  Oil  Company ;  Mr. 
Irving  V.  Augur,  geologist,  Los  Angeles;  Mr.  C.  G.  BuUis,  Los  Angeles. 


PETROLEUM    RESOURCES  OP   CALIFORNIA. 


11 


GENERAL  SUMMARY  OF  CONCLUSIONS. 
In  the  table  below,  the  production  figures  for  the  year  1900  and  again 
in  1920  are  shown.     It  will  be  noted  that  during  this  twenty-year 
interval  no  addition  to  the  principal  producing  counties  has  been  made. 

TABLE.* 


1900 

1920 

County 

Production, 
bbl. 

Percentage 
of  total 

Production, 
bbl. 

Percentage 
of  total 

Fresno    

Kern  

Los  Angeles 

Orange                 .                         --           ._ 

.547,960 
919,275 
1,722,887 
254,397 
183,486 
443,000 
248,915 

12.6 

21.3 

J8.9 

5.9 

4.3 

10.3 

5.7 

15,464,198 

52,120,532 

14,205,000 

15,800,000 

5,!>82,970 

2,122,000 

25,610 

14.7 
49.3 
13.4 
14.9 

Santa   Barbara  — 

Ventura                                                             -  -- 

5.7 
2.0 

4,319,950 

105,720,310 

•  From   the    Sixth  Annual   Report  of   the   State   Oil   and  Gas   Supervisor.     Vol.    6. 
No.  7.     Jan.,  1921. 

Exploration  has  opened  up  new  fields  within  these  districts,  increasing 
the  production  of  the  state  twenty-four  fold,  yet  it  has  failed  to  add  a 
single  noteworthy  field  outside  their  boundaries. 

The  principal  conclusion  to  be  drawn  from  this  report  is  similar  to 
that  shown  b}'  the  table.  An  examination  of  the  state  indicates  that  no 
field  of  any  appreciable  size  will  ])e  discovered  outside  the  two  present 
general  areas  of  production. 

These  two  districts  are  the  San  Joaquin  Valley  and  the  Coast  from 
the  Santa  Maria  River  south  to  the  Santa  Ana  River. 

In  the  San  Joaquin  the  most  promising  territory  for  development  lies 
along  the  west  side  of  the  valley.  In  the  Coast  area  it  consists  of  that 
portion  of  Los  Angeles  and  Orange  counties  lying  between  Santa  Monica 
and  Newport  and  south  of  the  San  Gabriel  Valley. 

It  is  also  evident  that  oil  in  appreciable  quantities  is  confined  to 
porous  sedimentary  rocks  of  the  Tertiary  period,  which  are  associated 
with  bodies  of  organic  shale  of  marine  origin.  The  greater  portion  of 
the  yield  comes  from  beds  of  Miocene  and  Pliocene  age. 

The  Cretaceous,  which  is  the  principal  sedimentary  formation  exposed 
in  northern  California,  .shows  numerous  seepages.  It  is  believed,  how- 
ever, that  it  will  not  produce  sufficient  oil  to  be  of  any  great  commercial 
importance. 

Those  fields  which  were  plainly  visible  to  the  geologist  and  prospector 
have  now  been  opened  up  to  development  work.  New  fields  in  the  future 
will  only  be  found  by  detailed  study  of  the  geology  and  topography  of 
the  state. 


statistics  for  1920, 

Total  production    (barrels) 105,720,310 

Total  proven  acreage  (acres) '  91*319 

Total   number  of  wells  producing IIII  9*042 

Average  production,  per  day,  per  well  (barrels) *  35 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  1 


o 


CHAPTER  I. 

General  Theory  of  the  Origin  and  Accumulation  of 

Oil  in  California. 

Organic   Theory   of   Origin. 

The  generally  accei)ted  theory  ainoii";  iieologists  as  to  the  origin  of 
petroleum  in  California,  is  that  which  assigns  to  it  an  organic  soifrce. 
According  to  this  theory  petroleum  is  the  result  of  the  slow  decomposi- 
tion and  (listiMatidn  of  animal  and  vegetal  matter  at  a  low  temperature, 
without  a  sut'ticieiit  supply  i»f  oxygen.  The  I'csult  of  this  chemical  reac- 
tion is  the  formation  of  li(|ui(l  liydrocai'bons.  known  as  ix'troleum,  or 
mineral  oil. 

Assuminii  that  the  above  theorx-  as  to  origin  is  cori'eet,  it  follows  that 
oil  in  California  nnist  necessarily  have  been  fornu'd  in  sedimentary 
rocks  and  in  particular  in  those  sedimentary  rocks  which  contained 
organic  material  in  ap|)recial)le  quantities. 

An  investigation  of  the  geological  format ion.s  of  the  state  indicates 
that  such  deposits  of  organic  nuiterial  are  present  in  renmrkable  quan- 
tities; ranging  in  the  geological  column  from  the  Cretaceous  to  the 
Pliocene  and  commonly  known  as  'organic  shales.' 

Further,  it  can  be  definitely  stated  that  all  hnown  deposits  of 
petroleum  in  Calif oniia  are  fouiul  //(  dose  association  u'itli  these  organic 
slialcs,  cither  in  or  above  than. 

Organic   Shales. 

The  organic  shales  were  originally  marine  deposits  of  fine  silt,  miiiijled 
with  the  remains  of  diatoms,  foraminifera  and  various  other  forms  of 
sea  life. 

Diatoms  are  a  low,  minute  form  of  plant  life  or  alga^,  having  a  frame- 
work of  silica.  Under  the  microscope  they  appear  as  round  dots  in 
the  shale  and  vary  in  size  from  0.1  mn.  to  1  nuL  and  apparently  form 
the  bulk  of  the  shale.  An  analysis  of  various  samples  of  California  oil 
shale  shows  that  they  vary  from  65  per  cent  to  85  per  cent  silica.  In 
view  of  these  facts  it  has  l)een  assumed  that  these  diatoms  are  the  chief 
.source  of  the  California  oil. 

After  the  diatoms,  the  ne.xt  most  al)undant  organisms  are  foramini- 
fera, an  animal  organism,  with  a  hard  calcareous  yhell,  generally  about 
2  mn.  in  length.  In  addition  the  shales  contain  numerous  sponge 
spicules,  fish  scales  and  impiessions  of  seaweed. 

The  diatom  and  foraminifera  lived  at  the  surface  of  warm  inland 
seas,  such  as  were  present  in  what  is  now  the  great  valley  and  coast 
regions  of  California,  during  the  various  geological  ages  from  the 
Cretaceous  to  the  present.  These  organisms  dying,  dropped  to  the 
bottom  of  the  seas  and  together  with  other  plant  and  animal  matter 
formed  an  ooze  or  organic  mud.  Then,  due  to  the  low  temperature  and 
absence  of  oxygen  in  (piantities,  a  very  slow  decomposition,  or  putrifica- 
tion  of  the  organic  parts,  took  place.  It  is,  however,  believed  that  no 
great  quantity  of  liquid  hydrocarbons  were  formed  at  this  stage.  These 
are  believed  to  have  been  formed  when,  due  to  earth  movements,  the 


14  CALIFORNIA    STATE    MINING   BUREAU. 

mud  or  ooze  was  uplifted  above  the  surface  of  the  sea  and  by  reason 
of  the  heat  and  pressure  due  to  these  movements  and  possibly  aided  by 
the  action  of  saline  waters,  distillation  of  the  shale  took  place,  which 
resulted  in  the  formation  of  petroleum. 

In  general  these  organic  shales  are  fine  grained  and  compact  in 
texture ;  light  in  weight ;  ranging  in  color  from  chocolate-brown,  purple 
and  maroon  to  light  gray  and  white.  They  vary  from  the  pure  soft 
earthy,  'chalky'  variety,  to  hard  flinty  porcelaneous  varieties. 

Migration  and  Accumulation. 

The  petroleum  thus  formed  in  the  organic  shales  was  probably  present 
at  first  in  minute  quantities  throughout  the  shale.  It  is  next  necessary 
to  account  for  its  concentration  and  accumulation  in  pools  such  as  now 
exist  in  the  California  fields.  To  explain  these  concentrations  in  pools 
it  will  be  necessary  to  assume  that  the  oil  migrated  from  the  shales  in 
which  it  formed  to  the  porous  reservoirs  where  it  is  now  found,  these 
reservoirs  in  practically  all  cases  being  porous  sands  either  in  the 
shales  or  directly  above  them.  Whereas  the  origin  of  the  petroleum 
from  the  organic  shale  may  be  readily  explained,  the  force  that  caused 
the  migration  and  accumulation  of  the  oil  is  not  as  yet  clearly  under- 
stood. All  that  is  certain  is  that  the  oil  has  migrated  and  accumulated 
in  pools  along  certain  geological  structures,  and  while  no  oil  in  commer- 
cial quantities  has  been  found  except  along  these  structures,  no  facts 
that  will  fit  all  existing  conditions  have  been  found  to  explain  the  reason 
for  the  accumulation. 

Before  giving  a  review  of  some  of  the  theories  for  accumulation  it 
would  be  well  to  describe  briefly  the  typical  geological  structure  wherein 
the  oil  in  California  is  found. 

The  contraction  of  the  earth's  surface  has  caused  folding  in  the 
rocks  that  form  its  crust.  There  are  several  different  kinds  of  folds. 
(See  Fig.  1,  page  15.)  When  the  strata  are  domed  up  in  an  arch  the 
structure  is  known  as  an  anticline.  The  trough  corresponding  to  this 
arch  is  known  as  a  syncline.  When  the  strata  have  been  tilted  in  one 
direction  only  the  structure  is  known  as  a  monocline.  When  the  apex 
of  an  anticline  or  cyncline  ceases  to  be  horizontal  it  is  said  to  plunge, 
and  similarly  when  the  axis  is  inclined  from  the  vertical  the  fold  is 
said  to  be  assymetrical.  When  forces  of  compression  have  caused  the 
strata  to  break  and  slip  along  a  definite  line,  faulting  takes  place. 
When  a  later  formation  is  deposited  upon  the  tilted  or  eroded  surface 
of  an  earlier  formation,  this  is  called  an  unconformity. 

Theories  as  to  Accumulation. 

(1)  Anticlinal  Theory.  This  theory  assumes  that  oil  being  of  a  less 
specific  gravity  than  water  rises  above  the  water  present  in  the 
porous  rocks  and  collects  in  the  highest  possible  point  in  an  upward  fold. 
The  factors  necessary  for  this  hypothesis  are,  (a)  saturation  of  the 
sand  with  oil,  gas  and  water;  (b)  folding;  (c)  porous  beds  between 
impervious  beds.  Oil  accumulating  in  this  manner  must  overcome  the 
friction  of  the  grains  of  the  porous  rocks  and  the  molecular  repulsion  of 
oil  and  water.  The  forces  in  favor  would  be  difference  in  gravity  of  the 
oil  and  water  and  the  inclination  or  dip  of  the  strata. 


PETROLEUM    RESOURCES   OF    CALIFORNIA. 


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16  CAIilFORNTA    STATE    MINING    BUREAU. 

(2)  A  second  theory  is  that  moving  waters  were  the  direct  agent  for 
tlie  accunndation.  That  is,  that  the  force  that  caused  the  niigration  was 
due  either  to  hydraulic  or  capillai-y  jii-essurc. 

Neither  of  the  abuve  theories,  however,  is  sunieicnl  to  e\i)lain  the 
enormous  gas  pressure  which  is  fouiul  in  California  fields  and  which  in 
nearly  all  cases  is  greater  Ihaii  that  wliicli  could  be  developed  by  any 
hydrostatic  pressure. 

Xor  do  they  explain  why,  when  the  forces  that  caused  the  original 
migration  are  no  longer  active,  the  oil  does  not  move  back  over  the 
l)ath  it  once  traveled. 

(3)  A  theory  whicli  has  recently  been  advanced  ])y  ^larcel  Daly' 
called   the   "diastrophic   theory,"   attributes   Ihe   migration    to   lateral 

,  pressure  caused  by  the  deformation  of  the  earth  crust.  The  forces  of 
i  compression  due  to  earth  movements,  he  believes,  have  transferred  their 
,  effects  not  only  to  the  solitl  matei'ial  of  the  eai-lli's  cnisl  l)ut  to  the 
tli(piids  contaiiu'd  in  the  porous  beds  as  well. 

■;      It  is  very  probable  that  all  of  the  above  theories  contain  some  element 
iof  truth,  and  the  forces  that  contributed  to  the  migration  nuiy  possibly 
'be  a  combination  of  all  of  these  forces.     That  is,  a  li(iuid  composed  in 
■parts  of  oil  and  water,  due  both  to  hydrostatic  pressure  and  compression 
.  from  earth  movements,  was  forced  to  migrate  along  planes  of  fracture 
and  unconformities  till  it  was  trapped  in  the  highest  parts  of  anticlinal 
■  folds.     Having  once  entered  the  fold  a  gradual  separation  of  the  oil, 
gas  and  water  took  place  due  to  the  dilference  in  specific  gravity  of 
these  substances.     The  pressure  over  and  above  that  whicli  is  due  to 
hydrostatic  forces  may  be  due  to  a  combination  of  further  earth  move- 
ments which  compressed  the  strata  in  which  the  oil  was  trapped,  and 
to  chemical  reactions  between  the  hydrocarbons  and  saline  waters,  which 
liberated  new  gases.     It  is  necessary  also  to  further  assume  that  once 
the  oil  entered  the  fold  that  the  various  points  of  entrance  gradually 
became  sealed  due  to  the  cementation  of  the  porous  sand  by  mineral 
bearing  waters  and  tar. 

However,  regardless  of  what  may  have  been  the  forces  that  caused 
accunndation,  it  can  be  definitely  stated  that  all  oil  in  commercial 
quantities  in  California  is  found  in  one  oi-  the  other  of  the  following 
geological  structures : 

(1)  Along  the  crests  of  anticlinal  folds  and  domes,  such  as  are  typified 
by  the  Buena  Vista  Hills  and  Elk  Hills  in  the  Midway,  and  the  ^loute- 
bello  Hills  and  Coyote  Hills  in  Southern  California. 

(2)  In  the  upper  i)art  of  i)lunging  synclines,  which  are  closely 
associated  with  i)roductive  anticlines.  The  Coalinga  syucline  is  a  type 
of  this  kind  of  a  pool. 

(3)  Along  the  upper  portions  of  monoclines  and  ti-uncated  anticlines 
lying  along  the  foothills,  which  are  undei-  the  influence  of  anticlinal 
domes  farther  out  in  the  valley.  This  ty])e  of  accumulation  has 
examples  in  the  West  Side  field  at  Coalinga,  the  west  portion  of  the 
Midway  field,  and  possibly  the  Kei'ii  River  field. 

(4)  Along  the  zone  of  fracture  and  in  upward  folds  influenced  by 
faulting.  Portions  of  the  Salt  Tiake  field  near  Los  Angeles  and  some 
portions  of  the  Puente  Hills  field  are  examples  of  this  type.  (See  Fig  2, 
page  17.) 

^  Daly,  Marcel.    The  Diastrophic  Theory.    Am.  Inst.  Min.  Eng.    Bull.  115. 


PETROLEUM    RESOURCES   OF    CALIFORNIA. 


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18  CALIFORNIA    STATE    MINING   BUREAU. 

In  general  those  fields  along  the  crests  of  anticlines  or  domes  have 
produced  the  largest  wells  while  those  along  fault  zones  the  smallest. 
Fields  situated  along  low-dipping  monoclines  are  the  longest  lived  and 
show  the  least  rate  of  decline. 

It  has  been  assumed  that  oil  travels  laterally  and  vertically — never 
downward — and  tlie  locations  of  all  known  pools  in  California  appear 
to  bear  out  this  assumption :  except  in  possibly  the  uppermost  sandstone 
of  the  fornuition  directly  below  an  organic  shale  bed,  no  oil  has  been 
found  in  formations  stratigraphically  below  a  known  bed  of  organic 
shale.  In  certain  eases  oil  has  been  found  in  formations  which  are 
geologically  older  than  the  organic  shale  which  is  present  in  that 
locality,  but  in  such  cases  its  presence  may  be  readily  explained  by  the 
fact  that  faulting  has  brought  the  older  formation  into  a  strati- 
graphic  position  above  the  organic  shale—a  reversal  of  their  normal 
position. 

The  reason  for  the  failure  of  the  oil  to  migrate  downward  ha.s  been 
attributed  to  the  facts  that  the  porous  sedimentary  rocks  of  the  oil 
field  are  saturated  with  water,  and  the  difference  in  specific  gravity 
of  the  oil  and  water  has  forced  the  oil  upward.  Similarly  should  the 
porous  rocks  not  contain  water,  the  oil  by  reason  of  gravity  should 
migrate  downward. 

Lateral  migration  has  probably  taken  place  along  planes  of  uncon- 
formities, and  porous  beds ;  and  vertical  migration,  along  faults,  cracks 
or  fractures  and  porous  beds. 

Reservoirs. 

Reservoirs  are  the  series  of  beds  in  which  the  oil  collects  along 
various  geological  structures  described  in  the  preceding  paragraphs. 

As  previously  stated  these  beds  are  either  in  the  organic  shale 
formation,  or  directly  above  it.  When  found  in  the  shales,  the  reservoir 
beds  are  either  very  fine  grained  sands,  or  hard,  flinty  beds  of  shale 
which  have  become  fractured  and  broken,  allowing  the  oil  to  collect  in 
the  voids  between  the  fractured  particles  of  the  .silicious  shale.  These 
two  cases  are  typified  by  the  fine  sands  in  the  so-called  'brown  shale' 
of  the  Belridge  and  Lost  Hills  fields,  and  in  the  fractured  flinty  zone, 
near  the  base  of  the  diatomaceous  shale  in  the  Santa  Maria  field. 

In  the  majority  of  cases,  however,  the  oil  has  collected  in  the  sand- 
stone beds  overlying  the  organic  shale.  The  lithology  of  these  beds  is  a 
very  important  consideration  in  the  accumulation  of  the  oil. 

First,  the  beds  must  be  porous  enough  to  absorb  the  oil  in  appreciable 
quantities.  The  porosity  is  not  dependent  upon  the  size  of  the  grains, 
but  rather  on  the  shape ;  regularity  in  size ;  and  arrangement.  A  fine- 
grained sand  composed  of  spherical  grains  all  of  one  size  and  arranged 
in  a  regular  manner,  will  have  greater  porosity,  than  a  coarse-grained 
sand  in  which  the  grains  are  irregular  and  flat,  so  that  they  may  be 
fitted  tightly  together,  thus  reducing  the  porosity.  The  size  of  the 
grains  afit'ect  the  character  of  the  oil.  In  general,  fine-grained  sands 
contain  the  light  oil,  while  coarse  sands  contain  the  heavy  viscous  oil. 
This  difference  in  the  character  of  the  oil  is  due  to  the  fact  that  the 
light  oil  will  move  readily  through  and  collect  in  the  fine-grained  sand, 


PETROLEUM    RESOURCES   OP    CALIFORNIA.  19 

whereas  the  thick  viseous  oils  are  too  tarry  to  move  freely  except  in 
coarse  sands.  The  so-called  shale  oil  zone  on  Twenty -five  Hill,  west  of 
Taft,  and  the  deep  'shale  oil  zones'  of  the  Belridge  field  are  examples 
of  this  differentiation  due  to  the  size  of  the  grains. 

Second,  there  must  be  a  difference  of  porosity  in  the  different  beds 
that  make  up  the  reservoir.  There  must  be  a  porous  bed  between  two 
impervious  beds.  Otherwise  the  oil  would  not  tend  to  concentrate  in 
certain  beds,  but  would  be  disseminated  throughout  the  reservoir,  in 
such  a  lean  saturation  that  extraction  in  commercial  quantities  by 
means  of  wells  would  be  impossible. 

The  Arroyo  Grande  field  is  a  good  example  of  lean  saturation.  In 
this  case,  the  oil  has  collected  in  the  Pismo  formation,  which  in  this 
particular  locality-  contains  no  impervious  shale  beds,  but  is  entirely 
made  up  of  sand.  Tlie  result  is  that  the  oil  has  disseminated  throughout 
the  entire  lUOO  feet  or  more  of  the  Pismo  formation,  in  such  lean  satura- 
tion, that  it  is  difhcult  to  obtain  wells  that  are  commercial  producers, 
although  tliere  is  enough  oil  present  if  concentrated  in  smaller  beds  to 
produce  oil  in  commercial  ([uantities. 

Third,  the  relationship  in  geological  time  between  the  source  and  the 
reservoir  has  an  important  bearing  upon  the  accumulation.  If  there 
is  too  great  a  time  interval  between  the  age  of  the  beds  in  which  the  oil 
formed  and  those  which  nuike  up  the  reservoir,  one  can  not  expect  the 
reservoir  to  contain  oil,  although  all  other  conditions  may  be  favorable. 
The  reason  for  this  is  obvious.  If  there  was  an  opportunity  for  the 
organic  shales  to  be  uplifted  and  eroded  before  the  deposition  of  the 
reservoir  formation,  the  oil  content  of  the  organic  shale  would  run  out 
and  be  lost,  before  an  opportunity  was  afforded  for  the  collection  of  the 
oil  in  the  reservoir. 

In  some  cases  after  the  reservoir  formation  has  been  deposited  and  the 
oil  collected  therein,  there  has  been  an  erosive  time  interval,  in  which  the 
reservoir  and  its  oil  content  were  eroded  away.  Subsequently  the  organic 
shales  were  again  lowered  beneath  the  surface  of  the  sea  and  a  second 
reservoir  formation  was  deposited.  This  in  time  was  uplifted  and 
folded.  In  this  ease  there  would  be  little  or  no  oil  in  the  second  reser- 
voir, as  the  greater  part  of  the  oil  content  of  the  organic  shales  had 
collected  in  the  first  reservoir  and  was  lost  in  the  erosive  time  interval. 
An  example  of  this  is  found  in  the  Pleyto  district  on  the  west  side  of 
the  Salinas  Valley.  Here  the  ^Monterey  shale  (Lower  Miocene)  and  the 
Paso  Robles  sands  (Upper  Pliocene)  are  folded  in  an  anticline,  yet 
there  is  no  appreciable  ainount  of  oil  in  tlie  Paso  Robles,  although  the 
general  conditions  for  accnnnilation  are  favorable.  It  is  probable  that 
this  failure  is  due  to  the  great  time  interval  between  the  ^Monterey 
shale  and  the  Paso  Robles  formation. 

Saturation   and    Recovery. 

The  capacity  of  oil  sands  and  the  amount  of  oil  recoverable  are  two 
important  considerations  in  determiniug  the  value  of  a  prospective 
field.  It  has  been  estimated  by  J.  0.  Lewis'  that  the  average  porosity 
for  California  sands  is  about  25  per  cent  of  their  volume,  provided  they 
are  completely  saturated.     Using  this  porosity,  Lewis  has  estimated 

» Lewis,  J.  O.    Bull.  148.    U.  S.  Bureau  of  Mines. 


20  CALIFORNIA    STATE    MINING   BUREAU, 

that  a  sand  one  foot  thick  covering  a  square  acre  in  extent  will  be 
capal)le  of  containing  19-iO  barrels  of  oil,  which  is  probably  a  very 
conservative  estimate. 

The  amount  of  oil  recovered,  however,  is  a  very  small  percentage  of 
that  which  is  contained  in  the  sand.  It  is  generally  agreed  that  not 
more  than  20  to  30  per  cent  is  extracted  by  means  of  wells. 

It  has  been  assumed  by  operators  that  when  a  well  ceases  to  produce, 
the  oil  sands  in  the  vicinity  have  been  exhausted.  This  is  not  the  case. 
In  all  probabilities  as  much  as  70  per  cent  of  the  oil  is  still  present  in 
the  sand,  and  the  reason  for  the  decline  of  the  well  is  due  to  the  exhaus- 
tion of  the  gas,  rather  than  the  oil. 

The  main  force  which  drives  the  oil  from  the  sand  into  the  well  is 
the  expanding  energy  of  the  gas  dissolved  in  the  oil.  It  has  been  shown 
that  California  oils  will  absorb  about  15  per  cent  of  their  volume  in 
natural  gas.  This  gas  is  absorbed  in  the  oil  in  the  same  manner  as 
soda  water  is  charged  with  carbon  dioxide.  When  a  well  is  drilled 
into  an  oil  sand,  the  i>ressure  is  suddenly  reduced  at  this  point  and 
consequently  the  liquefied- gas  expands  and  l)eLomes  a  true  gas.  This 
expansion  forces  the  oil  from  the  sands  into  the  well,  much  in  the  same 
manner  as  w^hen  the  cork  is  removed  from  a  l)ottle  of  soda  water  and 
the  dissolved  carbon  dioxide  gas  forces  the  liquid  out  of  the  moutli  of 
the  bottle.  The  expansion  of  the  liquefied  gas  from  the  oil  takes  place 
more  readily  in  light  oil  than  in  heavy  viscous  oils.  In  the  preceding 
paragraphs  it  was  stated  that  fields  along  the  crest  of  sealed  anticlines 
produced  the  largest  wells,  while  wells  located  on  low  dipping  mono- 
clines were  the  longest  lived  and  showed  the  slowest  rate  of  decline. 
This  can  be  explained  on  the  assumption  that  along  the  crest  of  anti- 
clines the  oil  for  the  most  part  is  of  a  comparatively  light  gravity  and 
the  liquefied  gas  expands  readily,  forcing  in  its  first  rush  to  freedom 
large  cjuantities  of  oil  into  the  well,  and  consequently  giving  a  large 
initial  production.  This  easy  expansion  allows  a  great  portion  of  the 
gas  to  escape  without  doing  its  full  share  of  moving  the  oil,  which 
results  in  a  rapid  decline  in  the  well  and  a  large  percentage  of  the  oil 
is  left  in  the  sands  without  any  force  to  drive  it  into  the  well.  On  the 
other  hand  in  low  dipping  monoclines,  such  as  the  Kern  River  field,  the 
oil  is  heavy  and  viscous  and  the  liquefied  gas  cannot  slip  out  of  the 
oil  readily  and  must,  to  escape,  move  the  oil  with  it.  This  probably 
explains  the  slow  rate  of  decline  in  fields  of  this  character. 

Areas  of  Accumulation. 

In  order  to  have  a  productive  field  there  must  not  only  be  present 
beds  of  organic  shale,  but  these  beds  must  be  of  considerable  thickness 
and  must  cover  a  large  area  in  extent.  It  frequently  luippens  that  wells 
located  on  opposite  sides  of  the  apex  of  an  anticline  differ  greatly  in 
their  productiveness.  In  most  cases  of  this  kind,  an  examination  of  the 
field  will  show  that  on  the  side  of  the  largest  well  the  organic  shales 
underlie  the  countr.y  over  a  considerable  area,  while  on  the  opposite 
side,  where  the  small  producer  is  found,  the  shales  are  present  only  in  a 
limited  area. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  21 

SUMMARY  OF  THE  CONDITIONS  NECESSARY  FOR  THE  ACCU- 
MULATION OF  OIL  IN  COMMERCIAL  QUANTITIES  IN  CALI- 
FORNIA. 

(1)  There  imist  be  present  in  close  association  with  the  prospective 
field,  thick  beds  of  orjianic  shale  to  serve  as  a  source  for  the  oil. 

(2)  There  nnist  be  present  either  in,  or  above,  the  organic  shale, 
porous  beds,  between  impervious  beds  to  act  as  a  reservoir  for  the  oil. 

(3)  The  reservoir  beds  must  be  folded  in  a  favorable  structure,  so 
as  to  cause  the  oil  to  accumulate. 

(4)  There  must  be  a  large  area  of  aecuiiiulation. 

(5)  There  must  not  be  too  great  an  interval  in  geological  time 
between  the  organic  shales  and  the  formations  composing  the  reservoir. 

Surface   Indications  of  Oil. 

The  best  surface  indication  tliat  a  district  contains  oil  is,  of  course, 
an  actual  seepage  or  iiow  of  oil  somewhere  in  that  area.  "While  all 
known  productive  fields  of  California  do  not  always  contain  seepages, 
notably  in  the  cases  of  closed  or  buried  fields,  nevertheless  if  the  under- 
lying formations  of  these  fields  are  followed  to  wliere  they  outcrop,  in 
every  case  actual  seepages  are  found. 

In  the  Tertiary  foi-mations  which  contain  the  asphaltic  oil,  seepages 
can  be  readily  found  as  the  evaporation  of  the  lighter  constituents  leave 
behind  a  heavy  tarry  residuum,  which  is  noticeable  long  after  the 
seepage  has  ceased  to  flow. 

In  the  case  of  the  liglit  oil  of  the  Cretaceous  formation,  this  evaporates 
entirely  upon  coming  to  the  surface  and  leaves  behind  no  residuum  and 
unless  the  seepage  is  actually  flowing,  it  is  not  likely  to  be  found. 

In  general,  seepages  occur  along  faults,  cracks,  and  where  the 
upturned  edges  of  the  formations  outcrop. 

'Gas  Blows'  and  burnt  shale  areas  are  also  good  indications  of  oil. 
True  'gas  blows'  are  found  along  faults,  cracks  and  on  the  outcrops  of 
formations  where  petroleum  gas  has  in  past  times,  or  is  at  the  present, 
escaping  into  the  air.  In  almost  every  case  this  gas  has  by  accident 
caught  fire,  which  has  resulted  in  the  burning  to  a  more  or  less  slaggy 
condition  of  the  formations  in  that  vicinity.  The  burning  has  changed 
the  color  of  the  beds  to  either  a  vivid  red  or  purple,  or  a  dull  white, 
depending  upon  wliether  or  not  the  beds  contained  iron  compounds! 

Frequently  in  wild-cat  districts  it  has  been  claimed  that  'gas  blows' 
are  present,  and  for  evidence  long  narrow  ])lack  and  l)rown  colored 
fragments  of  sandstone  have  been  presented.  It  is  the  opinion  of  the 
Avriter  that  these  so-called  'gas  blows'  are  in  no  way  connected  with 
petroleum  gas,  but  merely  reju-esent  a  concentration  of  iron  compounds 
along  cracks  ])y  means  of  moving  waters,  with  a  resulting  discoloration 
of  the  formation  to  black  and  brown. 

Notable  gas  blows  are  found  in  the  Buena  Vista  Hills  near  Taft  and 
in  the  McKittrick  district. 


22  CALIFORNIA    STATE   MINING   BUREAU. 

'Burnt  Shale  Areas'  are  eoniposed  of  shale  or  .sandstone  which  at  one 
time  or  another  contained  seepages  of  oil  and  which  by  accident  caught 
fire  and  burned,  leaving  the  shale  or  sandstone  in  a  condition  that 
resembles  a  brick  yard,  the  vivid  red  and  purple  colors  of  the  rocks 
being  particularl}^  noticeable  in  these  areas.  'Burnt  shale  areas'  are 
found  in  numerous  places  in  the  Santa  INIaria  and  McKittrick  Districts. 

Seepages,  gas  blows,  and  burnt  shale  areas  do  not  of  themselves 
mean  that  the  district  in  which  they  are  found  is  going  to  produce  oil 
in  commercial  qnantities.  There  must  also  be  present  suitable  structure, 
reservoir  beds  and  a  sufficiently  Avide  area  of  accumulation  and  origin. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  23 


CHAPTER  II. 
Description  of  the  Oil-Bearing  Formations  of  California. 

General   Geology  and   Structure  of  the   State. 

In  discussing  the  general  geology'  of  California,  the  state  may  be 
divided  into  five  provinces : 

(1)  The  Coast  Ranges.  (2)  The  Great  Central  Valley.  (3)  The 
Lava  Beds  of  the  Northeastern  Region.  (4)  The  Sierra  Nevada  Moun- 
tains.   (5)   The  Desert  Region  of  the  Southeast. 

(1)   THE  coast  ranges. 

In  the  extreme  nortliwestern  portion  of  the  slate,  in  the  counties  of 
Del  Norte,  Trinity  and  Siskiyou,  the  Coast  Ranges  are  known  as  the 
Siskiyou  or  Klaniatli  ^Mountains.  These  mountains  in  general  rise  to  an 
elevation  of  about  5000  feet  and  are  extremely  rugged.  The  prinoipai 
rivers  in  this  district  are  the  Klamath  and  the  Trinity  rivers.  The 
geological  formations  consist  of  slates,  schists  and  limestone,  of  Paleo- 
zoic age,  together  with  a  younger  series  of  altered  sands  and  shales, 
probably  of  Jurassic  age.  In  addition,  there  are  numerous  areas  of 
granitic  rocks  and  gneisses,  the  age  of  which  is  uncertain.  The  Jurassic 
sediments  contain  large  intrusive  masses  of  serpentine  and  l)asa]tic 
rocks.  All  of  these  sediments  have  been  sharply  folded  and  their 
structure  is  intricate  and  complex. 

South  of  the  Klamath  Mountains  and  north  of  the  Bay  of  San  Fran- 
cisco, the  Coast  Ranges  are  composed  of  a  series  of  long,  narrow, 
parallel  ranges  and  valleys.  These  ranges  have  an  elevation  in  general 
of  about  2100  feet,  and  present  to  a  marked  degree  a  sameness  in  eleva- 
tion. AYhen  viewed  from  a  liigli  point  this  region  appears  like  a  huge 
dissected  plateau.  A.  C.  Lawson'  has  stated  that  tliis  dissected  plateau 
represents  an  ancient  peneplain,  which  has  been  uplifted  from  a  nearly 
ba.se  level  condition  to  its  present  altitude,  this  uplift  being  marked 
by  at  least  six  marine  terraces.  Tlie  principal  river  valleys  consist  of 
the  Eel  River  in  the  north ;  the  Russian  River  in  the  central  portion  and 
the  Napa  and  Sonoma  valleys  in  the  south.  In  the  greater  portion  of 
this  area,  the  rocks  exposed  consist  of  cherts,  sandstone,  crystalline 
schists  and  serpentine  of  the  Franciscan  formation  (Jurassic?).  Along 
the  coast  there  is  a  narrow  strip  of  Cretaceous,  together  with  small 
areas  of  rocks  of  Tertiary  age.  On  the  great  valley  side  of  the  moun- 
tains a  great  thickness  of  Cretaceous  sediments  is  exposed  together 
with  small  isolated  patches  of  rocks  of  Tertiary  age. 

South  of  the  Bay  of  San  Francisco,  the  Coast  Ranges  in  general 
trend  nearly  parallel  to  the  Coast.  The  average  elevation  is  from  2000 
to  3000  feet,  except  south  of  Los  Angeles,  where  the  San  Gabriel,  San 
Bernardino  and  San  Jacinto  Ranges  reach  altitudes  from  10,000  to 
11,000  feet.  The  most  prominent  topographic  feature  is  the  series  of 
rather  broad  interior  valleys  which  separate  the  different  ranges  between 
San  Francisco  and  Los  Angeles.  South  of  Los  Angeles,  these  valleys  are 
conspicuous  by  their  ab.sence  and  the  general  trend  of  the  small  valleys, 

'Lawson,  A.  C.    Univ.  of  Calif.   Bull.    Dept.  of  Geology,  Vol.   1,  No.   8.    The  Geo- 
morphogeny  of  the  Coast  of  Northern  California. 


24  CALIFORNIA    STATE    MINING   BUREAU. 

that  are  present,  is  at  right  angles  to  the  Coast.  Beginning  at  the 
north  these  interior  valleys  consist  of  the  Santa  Clara  Valley  in  Santa 
Clara  Comity;  the  San  Benito  and  Trcs  Finos  valleys  in  San  Benito 
Connty ;  the  Salinas  A'alley  in  ^lonterey  County  and  northern  San  Luis 
Obispo  County;  the  Cuyania  and  Santa  Ynez  valleys  in  Santa  Barbara 
County;  the  Simi  Valley  and  the  Valley  of  the  Santa  Clara  River  in 
Ventura  County;  the  San  Gabriel  and  San  Fernando  valleys  of  Los 
Angeles  County;  and  lastly,  the  Valley  of  the  Santa  Ana  River  in 
Orange  County. 

The  principal  ranges  consist  of  the  Santa  Cruz  ^Mountains,  which  lie 
along  the  boundary  between  Santa  Clara  and  Santa  Cruz  counties; 
the  Diablo  Range,  which  forms  the  ea.stern  edge  of  tlie  Coast  Ranges 
from  Suisun  Bay  to  Coalinga  :  tlie  Cabilan  Range,  which  lies  between 
San  Benito  and  IMonterey  counties;  the  Santa  Lucia  Range,  which 
forms  a  mountainous  region  along  the  coast  of  ]Monterey  and  San 
Luis  Obispo  counties:  the  Temblor  Range,  which  lies  in  eastern  San 
Luis  Obispo  and  western  Keni  counties ;  in  Santa  Barljara  are  the  San 
Rafael  and  Santa  Ynez  ranges,  which  have  a  northwest  direction ;  the 
Topatopa  Mountains  in  Ventura  County  and  the  Santa  ]\Ionica  Moun- 
tains in  western  Los  Angeles  County,  trending  almost  due  east  and  west. 
The  San  Gabriel  ^Mountains  in  Los  Angeles  County,  the  San  Bernardino 
Range  in  San  Bernardino  Count}',  tlie  San  Jacinto  Range  in  River- 
side County,  and  the  Peninsula  Range,  which  extends  southward 
through  San  Diego  County  into  Lower  California  separate  the  desert 
tegion  from  the  Coastal  Plane  of  Southern  California.  These  ranges, 
both  in  topography  and  geolog}'.  bear  a  marked  resemblance  to  the 
Sierra  Nevada  and  may  be  regarded  as  a  southward  extension  of  this 
system.  The  Santa  Ana  JMountains  in  Orange  County  may  be  regarded 
a-s  the  most  southward  range  of  the  true  Coast  Range  type. 

For  the  most  part  the  Coast  Ranges,  between  San  Francisco  Bay 
and  the  Santa  Ana  ^Mountains,  are  composed  of  unaltered  sediments 
of  Cretaceous  and  Tertiary  age.  Exceptions  to  this  condition  are 
found  in  the  central  portion  of  the  Diablo  Range,  where  large  areas 
of  the  Franciscan  (Jurassic?)  are  exposed  and  in  the  Santa  Lucia  and 
Gabilan  ranges  which  consist  almost  wholly  of  highly  altered  sedi- 
ments of  Paleozoic  age,  together  with  granite  rocks  and  gneisses.  It 
is  in  the  Tertiary  sediments  which  lie  along  the  eastern  and  western 
flank  of  the  middle  Coast  Ranges,  that  the  principal  oil  fields  of  Cali- 
fornia are  found.  South  of  the  Santa  Ana  River,  the  sedimentary 
rocks  are  limited  to  a  narrow  strip  along  the  Coastal  Plane  and  a  few 
isolated  patches  in  eastern  Riverside  County.  The  San  Gabriel,  the 
San  Bernardino,  the  San  Jacinto  and  the  Peninsula  Range  are  com- 
posed of  granitic  rocks. 

(2)  THE  GREAT  CENTRAL  VALLEY. 

The  Great  Central  Valley  of  California  com[)rises  an  area  of  al)()ut 
16,000  square  miles  and  includes  the  Sacramento  Valley  in  the  north 
and  the  San  Joaquin  Valley  in  the  south.  The  north  end  of  the  Sac- 
ramento Vallev  is  at  Redding,  Shasta  Countv,  where  it  has  an  elevation 


PETROT.EUM    RESOURCES   OF    CATJPORNIA.  25 

of  600  feet  ami  a  witltli  of  about  trn  miles.  Kxtciidiim  southward,  its 
width  increases  to  20  miles  at  Ked  BlutV.  40  miles  at  Willows,  and  45 
miles  at  Snisiin  Hay,  into  wliieli  the  Saei-amento  River  disrhari^es. 
The  San  -Toaqnin  has  a  width  of  alxnit  30  miles  at  its  northern  extremity 
near  Stoekton.  thence  it  increases  in  width  as  it  extends  southward, 
till  it  reaches  a  maxinnnn  of  60  miles  near  llanford.  Kings  County. 
At  the  base  of  the  Tehacliapi  Mountains,  in  Kern  County,  where  the 
vallev  ends,  it  has  a  width  of  about  :^(V  miles  and  an  elevation  of  al)Out 
1000  "feet. 

The  valley's  surface  is  almost  entirely  covered  by  alluvium,  but 
undoubtedly  formations  of  Cretaceous  and  Tertiary  age  are  present 
beneath  the  surface.  The  only  notable  interruption  in  the  surface  con- 
tinuity is  formed  by  the  jNlarysville  Buttes,  a  vulcanic  mass  in  the 
central  part  of  tlie  Sacramento  Valley. 

Between  Red  Blutt'  and  Suisun  Bay,  the  alluvium  of  the  valley  floor 
rests,  on  its  western  edge,  against  I'ocks  of  Cretaceous  age,  exposed  in 
the  foothills  of  the  Coast  Ranges.  South  of  San  Francisco  Bay,  the 
valley  floor  Is  terminated  on  its  western  side  by  rocks  of  Tertiary 
age,  exposed  in  low-rounded  hills  that  .jut  out  into  the  valley's  floor. 
The  large  producing  oil  fields  of  the  San  Joaquin  Valley  are  found  in 
the.se  low  hills.  On  the  eastern  edcre,  or  Sierra  side,  the  alluvium  of 
the  valley  floor  rests  for  the  most  part  against  the  metamorphic  and 
crystalline  rocks  of  the  Sierra  Nevada  and  except  for  an  area  of 
Miocene  around  Bakersfield  and  a  snudl  thickness  of  Tejon  bet\veen 
the  ]\rariposa  and  the  American  rivers,  sedinumtary  rocks  of  Tertiary 
age  are  conspicuous  by  their  absence.  In  the  extreme  northeastei-n 
part  of  the  Sacramento  Valley,  there  is  a  large  area  of  volcanic  tuff 
and  lava  exposed. 

(3)  THE  LAVA  BEDS  OF  THE  NORTHEASTERN  REGION. 

This  lava  covered  region  forms  an  extensive  area  in  the  northeastern 
portion  of  the  state  and  includes  the  counties  of  Modoc,  Lassen  and  the 
eastern  parts  of  Siskiyou,  Shasta  and  Tehama  counties.  The  central 
and  northern  portions  of  this  area  form  a  plateau  which  is  between 
4000  and  5000  feet  in  elevation.  In  the  northeast  the  Warner  Moun- 
tains reach  an  altitude  of  8000  feet.  In  the  south  the  Las.sen  Peak 
Range  reaches  an  altitude  of  more  than  10,000  feet,  and  on  the  west, 
:\rount  Shasta  towers  at  an  altitude  of  14.880  feet. 

Practically  all  this  region  is  covered  with  lava,  probably  of  late  Ter- 
tiary age.  In  a  few  places  there  are  lake  bed  deposits  of  loose  sands 
and  clays  and  fresh  water  diatomaceous  shale. 

(4)  SIERRA    NEVADA. 

The  Sierra  Nevada  is  the  dominating  physical  feature  of  the  state. 
It  forms  a  great  single  range  that  extends  from  the  base  of  the  Lassen 
P<vak  Range  southward  to  T<\ion  Pass  in  nru'thern  liOs  Angeles  County. 
On  the  western  side  it  slopes  gently  up  from  the  great  valley  to  its 
crest  and  thence  drops  off  abruptly  to  the  desert  on  its  eastern  edge. 
In  its  northern  portions  it  reaches  an  altitude  of  from  9000  to  10,000 
feet  and  southward  it  rises  to  its  greatest  height  in  Blount  Whitney, 


26  CALIFORNIA    STATE    MINING   BUREAU. 

an  elevation  of  14,501  feet.  In  its  northern  and  western  parts  there 
are  lar2:e  areas  of  altered  sedimentary  and  igneous  rocks  which  are 
highly  mineralized.  In  the  south  and  east  the  range  is  almost  entirely 
composed  of  granitic  rocks, 

(5)    THE   SOUTHEASTERN    DESERT   REGION. 

This  district  consists  of  a  number  of  detached  mountain  ranges 
which  are  separated  by  arid  valleys  and  flat  stretches  of  the  desert. 

The  principal  ranges  are  the  White  ^fountains  in  Mono  County;  the 
Coso  Range,  southeast  of  Owens  Lake ;  the  Panamint  Range  along  the 
^vestern  border  of  Death  Valley ;.  the  Araargosa  Range  in  eastern  Inyo 
County ;  the  Kingston  Range  in  northeastern  San  Bernardino  County, 
and  the  Hathaway,  Clnicka walla  and  Chocolate  mountains  on  the 
eastern  border  of  the  Imperial  Valley.  These  ranges  vary  in  altitude 
from  3000  to  11,000  feet. 

Among  the  valley  areas  are  the  Colorado  Desert  in  the  southeastern 
part,  the  Imperial  Valley  in  the  extreme  south  and  the  Mojave  Desert 
and  the  Death  Valley  regions  in  the  north. 

The  mountain  ranges  for  the  most  part  consist  of  altered  sediments 
of  Paleozoic  age.  together  with  granitic  rocks  and  lava  flows.  In 
eastern  San  Bernardino  County  there  are  lake  bed  deposits  of  ]\Iiocene 
and  Pliocene  age.  In  the  Imperial  Valley,  there  are  exposures  of  fine 
silts  and  clays  of  ]\[iocene  age. 

Faults. 

The  two  major  lines  of  faulting  are  (1)  the  San  Andreas  fault, 
which  lies  in  the  Coast  Ranges  and  extends  from  Cape  ^Mendocino,  in 
Humboldt  County,  to  the  Colorado  Desert,  a  distance  of  600  miles. 
It  is  marked  throughout  the  greater  part  of  this  distance  by  narrow 
troughlike  vallej's  and  steep  mountain  slopes.  (2)  The  great  fault 
marking  the  eastern  base  of  the  Sierra  Nevada,  along  which  the  great 
Sierra  Range  was  uplifted. 

Non-Oil-Bearing   Formations. 

A  little  less  than  one-half  of  the  state's  surface  is  made  up  of 
crystalline  rocks.  The  term  crystalline  rocks  ^vill  be  used  in  this 
report  to  designate  rocks  of  igneous  and  metamorphic  origin.  These 
rocks,  by  the  very  nature  of  their  being,  can  not  be  expected  to  con- 
tain petroleum,  as  they  are  the  result  of  intense  heat  and  pressure, 
and  in  addition  contain  no  organic  material  which  might  form  petro- 
leum. Occasionally  small  quantities  of  oil  have  been  found  in  crystal- 
line rocks,  namely  in  a  crystalline  schist  at  Placerita  Canyon,  Los 
Angeles  County,  and  in  serpentine  rocks  on  Bear  Creek,  Colusa  County. 
Neither  of  these  deposits  have  much  commercial  value  and  are  inter- 
esting only  for  their  uniqueness.  The  collection  of  oil  in  both  cases, 
is  undoubtedly  due  to  the  fact  that  organic  shales  at  one  time  over- 
laid the  crystalline  rocks  and  a  small  portion  of  their  oil  content, 
filtered  down  into  the  fractures  and  crevices  of  the  underlying  crystal- 
line formation. 

It  will,  therefore,  be  assumed  in  this  report  that  crj'stalline  rocks  in 
general  are  not  capable  of  containing  oil  in  commercial  quantities  in 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  27 

California  and,  discussing  the  different  districts  in  detail,  such  areas  as 
contain  these  rocks  will  be  dismissed  from  consideration. 

The  second  type  of  rocks  tliat  will  be  considered  as  nonoil-bearing 
in  California  are  those  sedimentary  rocks  of  pre-Crctaceous  age.  The 
rca.son  for  this  assumption  is  based  upon  the  following  facts:  (1)  These 
rocks  for  the  most  part  have  been  highly  altered  and  deformed  and 
any  possible  oil  content  has  been  destroyed  by  metamorphism. 
(2)  There  are  no  bodies  of  dialomaceous  shale  present,  (3)  although 
limestone  beds,  which  are  oil  bearing  in  otbcr  states,  occur  in  consider- 
able thickness  from  the  Cambrian  to  the  Triassic  in  California,  great 
mountain  making  movements  have  so  shattered  and  altered  these  beds, 
that  they  are  practically  crystalline  rocks  and  contain  no  structure  that 
would  be  favorable  for  tlie  accunuilation  of  oil.  (4)  There  is  no 
authentic  record  of  any  occurrence  of  petroleum  in  California  in  sedi- 
mentary formations  older  than  the  Cretaceous.  It  is,  therefore,  the  opin- 
ion of  the  writer,  that  no  oil  in  commercial  quantities  will  be  found  in 
California  in  formations  older  than  the  Cretaceous. 

OIL-BEARING  FORMATIONS. 

As  stated  in  Chapter  I,  all  known  occurrences  of  oil  in  California  are 
found  in  close  formation  with  beds  of  organic  shale,  commonly  known 
as  diatomaccous  shale.  These  beds  range  in  age  from  the  Cretaceous  to 
the  Pliocene.  Therefore,  in  this  report,  the  only  formations  which  will 
be  considered  as  potential  sources  of  petroleum  will  be  sedimentary 
formations  from  the  lower  Cretaceous  to  the  upper  Pliocene. 

Cretaceous. 

For  the  purpose  of  this  report  the  Cretaceous  will  be  considered  as 
having  two  major  units  only,  the  lowermost  beds  known  as  the  Knox- 
ville,  and  the  upper  beds  known  as  the  Chico.  (The  Horsetown  beds 
will  be  regarded  as  upper  Knoxville.) 

The  Knoxville  formation  consists  as  a  whole  of  dark,  fine-grained, 
thinly-bedded,  more  or  less  carbonaceous  shales.  Alternating  with  the 
shale  beds  are  thin  lenses  of  fine-grained  sandstone.  A  few  lenses  of 
pebbly  conglomerate  occur  near  the  top  of  the  formation.  In  general, 
the  Knoxville  is  characterized  by  a  predominance  of  shale.  It  occurs 
in  the  following  areas  (1)  along  the  west  side  of  the  Sacramento  Valley 
from  Redding  to  Suisun  Bay,  (2)  along  the  west  side  of  the  San  Joa- 
quin Valley  from  Suisun  Bay  to  a  point  just  south  of  Coalinga,  (3)  in 
a  narrow  strip  in  northeast  Humboldt  County  and  southwest  Trinity 
county,  (4)  in  small  patches  along  the  Coast  from  San  Francisco  as 
far  soutli  as  San  Luis  Obispo.  It  is  best  developed  along  the  we.st_side 
of  the  Sacramento  Valley,  where  it  reaches  a  maximum  of  about  25,000 
feet.  In  the  San  Joaquin  Valley  it  has  an  average  thickness  of  about 
4000  feet.  The  most  characteristic  fossils  are  the  Aucella  piochi  and 
the  Aucella  crassicoUis.  No  oil  in  commercial  quantities  has  as  yet 
been  obtained  in  the  Knoxville.  Seepages  of  light  green  and  dark 
amber-oil,  of  a  paraffine  base  occur  in  the  Knoxville  shales  of  Colusa 
Countv,    (a  discussion  of  the  possibilities  of  this  region  is  given  in 


28  CALIFORNIA    STATE   MINING   BUREAU. 

Cliai'ter  VI).  It  is  the  opinion  of  the  writer  that  no  great  production 
of  oil  can  be  expected  from  the  Knoxville  formation. 

The  Chico  formation  consists  in  general  of  massive  medium  coarse 
bluo-gray  and  greenisli  sandstone.  Avhich  tnrns  to  a  tawny  brown  on 
weathering.  Interbedded  with  the  sandstone  are  thin  beds  of  dark 
gray  shale.  In  the  Sacramento  Valley,  near  the  bottom  of  the  forma- 
tion, are  several  beds  of  conglomerate,  made  up  of  pebbles  of  crystal- 
line rooks.  In  Solano  and  Volo  connties,  the  Chico  contains  several 
beds  of  dark  carbonaceous  shale  ranging  in  thickness  from  100  to  500 
feet.  Along  the  west  side  of  the  San  Joaquin  Valley  from  Coalinga  to 
Livennore  pass,  the  uppermost  Chico  is  called  the  Moreno  formation 
and  consists  of  almost  2000  feet  of  diatomaceous  and  foraminiferal 
shale,  this  shale  being  the  original  source  of  the  Cretaceous  oil  found 
in  the  Oil  City  field. 

In  general  the  Chico  is  characterized  by  a  predominance  of  sandstone. 

It  occurs  in  the  following  areas  (1)  along  the  west  side  of  the  Sacra- 
mento and  San  Joaquin  valleys;  (2)  along  the  east  side  of  the  Sacra- 
mento Valley  north  of  Qroville;  (3)  along  the  coast  of  northern  Cali- 
fornia from  the  mouth  of  the  Russian  River  to  Cape  INIendocino;  (4)  in 
the  southern  Coast  Ranges  particularly  in  the  Santa  Ana  and  Santa 
jMonica  mountains.  Over  the  entire  state  it  has  a  maximum  thickness 
of  about  8000  feet. 

The  only  oil  in  commercial  quantities  which  has  been  obtained_£rom 
the  Chico  is  at  Coalinga,  in  the  old  Oil  City  field,  where  a  totaLof 
twelve  wells  produced  on  an  average  135  liarrels  per  day,  for  the  ;v^ar 
1920.  There  are  seepages  of  light  green  oil  in  the  Chico  of  Humboldt 
County  and  in  Yolo  and  Solano  counties  it  has  been  reported  that  tli£re 
are  seepages  of  light  green  oil  in  the  Chico  shales. 

In  general  the  Cretaceous  oil  varies  in  color  from  amber  and  light 
green  to  white.  It  is  of  a  paraffine  base  and  averages  about  52°  Baume 
in  gravity. 

It  is  extremely  doubtful  in  the  opinion  of  the  writer,  that  a  large 
production  can  ever  be  expected  from  the  Cretaceous  formation,  or  that 
it  will  produce  in  commercial  quantities  except  in  the  Coalinga  district, 
where  it  contains  thick  beds  of  diatomaceous  shale  and  is  folded  in  a 
favorable  structure. 

Eocene. 

The  Eocene  in  this  report  will  be  considered  as  having  three  divisions, 
the  lower  or  IMartinez,  the  middle  or  Meganos  and  the  upper,  or  Tejon. 

The  Martinez  formation  consists  of  thick-bedded,  medium  coarse- 
grained, greenish-gray  sandstone.  It  contains  some  minor  beds  of  shale 
and  conglomerate.  The  maximum  thickness  is  about  4000  feet.  It 
occurs  in  the  following  areas:  (1)  Santa  Ana  IMountains.  (2)  Santa 
Monica  IMountains.  (3)  Ventura  Connty.  (4)  San  Francisco  Bay 
region.  (5)  Lake  County.  (6)  Pi-o])a]ily  certain  sands  and  shales 
along  the  valley  of  the  Eel  River  in  Ilumlioldt  County. 

Chai'actcristic  fossils  nrr  ('uculhia  watltcu^saju-niid  Tiirritclla  padic- 
cocnsis^  There  is  no  piuduetion  of  oil  in  commercial  quantities  from 
tUe  Martinez^ 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  29 

The  ^reg:anos  formation  consists  mainly  of  marine  shales  with  some 
sandstone  and  conj^lomerate.  In  the  Simi  N^dley  the  shales  are  appar- 
ently earbonaeeons.  They  vary  in  eolor  frnm  pnrph^  to  'n-t^y  and  avt^ 
tliin-hedded  and  rather  fine-prrainecj  in  texlnre.  In  the  vicinity  of  San 
Diego  the  xMegano.s  consists  of  fine  clay  shales,  and  near  Snisun-Fair- 
field.  and  in  the  Monnt  Diahh)  region  it  consists  of  jiink  diattnnaceous 
shales. 

The  best  known  ontcrops  occur  as  follows:  (1)  San  Diego  County. 
(2)  Santa  Monica  Mountains.  (3)  Simi  Valley.  (4)  San  Emigdio 
i\Ionntains.  (4)  INIount  Diablo.  Cliaracteristic  fossils  are  Turritella 
andcrsoni  and  Xatica  }ia)>>iibali. 

The  i\Ieganos  shales  are  probal)ly  the  source  of  the  oil  found  in  the 
Tejon  sandstone  of  the  Simi  Valley  and  the  Sespe  district  of  Ventura 
County. 

The   Te.ion    consists   of   a    hard    COf^rsp-gr^iiripd    liffhf    ypHnw    and  -gray 

sandstone^  The  basal  sands  in  the  San  Joaquin  Valley  and  Southern 
California  are  frequently  of  a  reddish  color  due  to  iron  oxide.  On  the 
east  side  of  tlie  Sacramento  Valley,  the  Tejon  is  known  as  the  lone  and 
consists  of  about  lOUO  feet  of  fine  clays  and  some  sandstone.  The  maxi- 
mum thickness  over  the  entire  state  is  about  5000  feet.  Beds  of  li^ni_t^ 
and  red  and  yellow  pottery  clays  are  eharaetoristic  nf  ThT^' Tpj'^''  In, 
Ventura  County  the  Topa-Topa.  formation  uiay.be  considered  as  behig 
of  Tejon  age. 

The  Tejon  occurs  in  the  following  areas:  (1)  San  Diego  County. 
(2)  Santa  Ana  Mountains.  (3)  Ventura  County.  (4)  Santa  Ynez 
IMountains.  (5)  West  side  of  the  San  Joaquin  Valley.  (6)  East  side 
of  the  Sacramento  Valley.  (7)  Isalated  areas  in  the  northern  Coast 
Ranges. 

Characteristic  fossils  are  the  Venerkardia  plamcosta  and  Turrit  ells 

In  the  Simi  and  Sespe  regions  of  Ventura  County,  the  Teion  is  thp 

principal  nil-hpflring  fm-umtimi  niul  vip1d«  a  oTPPnit;h.h1a^1r  ml  nf  abmit 
40°  Baume  gravity,  whifli  has  accnmnlfltprl  hi  fbp  Tpjon  sands  ffftni 
the  underlying  iNIeganos  shales.  In  the  Coalinga  field,  the  Tejon  con- 
tains some  oil  which  has  migrated  from  the  ^Foreno  shales.  In  the 
Kreyenhagen  Hills  of  Kings  County,  the  Tejon  sands  yield  small 
amounts  of  green  oil. 

Oligocene. 

The  Oligocene  has  been  definitely  recognized  in  the  following  areas: 

(1)  .Ventura    County    where    it   is   known    as   the    Sespe    formation. 

(2)  West  side  of  the  San  Joaquin  Valley  from  the  Coalinga  district  to 
Livermore    Pass,    where    it    is    known    as    the    Kreyenhagen    shales. 

(3)  Santa  Cruz  Mountains,  where  it  is  known  as  the  San  Lorenzo 
series. 

The  Kreyenhagen  shales  may  be  regarded  as  lower  Oligocene  and 
consist  of  pink  and  chocolate  colored  diatomaceous  and  foraminiferal 
shales;  clay  shales;  and  a  little  sandstone.  They  have  a  maximum 
thickness  of  about  1500  feet,  and  are  the  original  source  of  the  main  body 


30  CALIFORNIA    STATE   MINING   BUREAU. 

of  petroleum  in  the  Coalinga  field,  which  has  undoubtedly  migrated 
from  these  shales  into  the  overlying  Vaqueros  sandstone. 

The  characteristic  fossils  are  Leda  lincolncnsis  and  Fusinus  lincoln- 
ensis. 

The  Sespe  formation  is  found  in  Ventura  County  and  consists  of 
about  3500  feet  of  white,  red  and  brown  sandstone,  interbedded  with 
beds  of  purple  and  red  clays.  In  the  Simi  Valley,  this  formation  con- 
tains several  prominent  beds  of  conglomerate.  There  are  no  known 
fossils  in  this  formation  and  it  probably  in  part  represents  a  conti- 
nental deposit.  In  the  Sespe  and  South  ^Mountain  districts  of  Ventura 
County,  it  is  the  principal  oil-bearing  formation,  the  oil  having  collected 
in  the  Sespe  from  the  underljang  Eocene  shales.  The  oil  is  black  and 
averages  about  32°  Baume  gravity.  The  Sespe  may  be  regarded  as 
upper  Oligocene. 

The  San  Lorenzo  formation  is  found  in  the  Santa  Cruz  IMountains 
and  consists  of  about  3000  feet  of  fine-grained  sandstone  and  shale. 
Characteristic  fossils  are  Cardium  lorcnzanum  and  AcUa  dalli.  The 
San  Lorenzo  formation-  is  not  regarded  as  an  oil-bearing  formation. 
However,  at  IMoody  Gulch  in  the  Santa  Cruz  ^Mountains  it  contains  a 
small  amount  of  light-gravity  oil,  which  has  migrated  along  a  fault 
plane  from  the  Monterey  shale  into  the  San  Lorenzo. 

Approximately  1.300,000  barrels  of  oil  were  produced  from  beds  of 
Oligocene  age  during  the  year  1920,  which  is  about  1.3  per  cent  of 
the  entire  production  of  the  state. 

Miocene. 

The  Miocene  may  be  regarded  as  having  two  main  divisions,  the 
lower  Miocene  which  contains  the  so-called  Monterey  Series  and  the 
upper  Miocene,  which  contains  the  San  Pablo  Series  in  the  San  Fran- 
cisco Bay  region  and  the  Santa  Margarita  Series  of  middle  California. 

The  ]\Ionterey  Series  is  a  name  which  has  been  recently  applied  by 
the  U.  S.  Geological  Survey  to  the  lower  portion  of  the  jNIiocene  in  Cali- 
fornia and  covers  what  was  formerly  recognized  as  two  separate  forma- 
tions, viz:  (1)  The  Monterey  shale  (called  in  various  reports  of  the 
U.  S.  Geological  Survey,  Puente  shale,  Monterey  shale,  the  Modelo 
formation,  Saliuas  shale  and  ^Maricopa  shale).  (2)  The  Vaqueros 
sandstone. 

Inasmuch  as  the  terms  Monterey  shale  and  Vaqueros  sandstone 
have  become  fixed  by  long  usage  among  the  oil  men  of  California  to 
designate  two  of  the  most  important  oil  horizons  of  the  state,  it  is  the 
opinion  of  the  writer  that  this  terminology  should  remain  in  discixssing 
oil  field  geology. 

For  the  purpose  of  this  report,  while  the  term  Monterey  Series  will 
be  regarded  as  designating  the  lower  jMiocene,  the  term  ]\Ionterey  shale 
will  be  continued  in  use  to  designate  the  upper  portion  of  the  series, 
which  is  mainly  shale,  and  Vaqueros  .sandstone  will  be  used  for  the  lower 
portion.^ 

'Note.  Prof.  B.  L.  Clark  of  the  University  of  California  hns  recently  proposed  the 
name  of  Temblor  to  designate  the  upper  portion  of  the  Monterey  Series  and  the 
writer  has  used  this  name  in  the  correlation  tables  (Plate  II)  as  the  standard  name 
for  the  upper  portion  of  the  Monterey  Series. 


PETROLEUM   RESOURCES  OF   CALIFORNIA.  31 

The  lower  portion  of  the  ^lonterey  Series,  which  is  mainly  sandstone 
consists  of  liard  yollowisli-<iray  sandstones  and  conglomerates.  It  has 
a  maximum  thickness  of  abuut  5000  feet.  The  Vaqneros  outcrops  in 
the  following  areas:  (1)  Santa  Cruz  IMountains.  (2)  East  side  of  the 
Santa  Lucia  Range  and  in  the  Salinas  Valley  district.  (3)  Santa  Ynez 
Mountains  and  Santa  ^Maria  district.  (4)  West  side  of  the  San  Joa- 
quin Valley.  (5)  Santa  ^lonica  and  Santa  Ana  mountains.  It  is 
not  known  north  of  the  Bay  of  San  Francisco  or  east  of  the  Coast 
Ranges.  Characteristic  fo.ssils  are  Fecten  magnolia  and  Tiirritella 
inezana. 

The  Vaqueros  has  l)een  found  ])ruductiv('  in  the  following  regions: 
^Coalinga  district  where  it  is  the  principal  oil-bearing  formation,  the 
oil  having  migrated  and  collected  in  the  Vaqueros  sands  from  the 
underlying  Kreyenliagen  shales.  (2)  In  the  Santa  Maria  field,  the 
third  oil  zone  is  believed  to  l)e  in  the  Vaqueros,  the  oil  having  migrated 
from  the  Monterey  shales,  probably  along  a  fault  plane  into  the  upper- 
most Vaqueros  beds.  (3)  At  Moody's  Gulch  in  the  Santa  Cruz  Moun- 
tains, the  Vaqueros  sands  contain  a  small  quantity  of  light  oil,  where 
they  have  been  brought  in  contact  by  faulting  with  the  ]\Ionterey  shales. 
The  Vaqueros  formation  yielded  in  1920  about  16,000,000  barrels  of  oil 
or  16  per  cent  of  the  yield  of  the  entire  state. 

The  IMonterey  shale  formation  in  this  report  includes,  tlie  Puente 
shale,  the  Modelo  formation,  the  Salinas  shale  and  tlie  lower  portion 
of  the  INIaricopa  shale.  It  consists  mainly  of  diatomaceous  shale  with 
some  interbedded  sandstone  and  volcanic  ash.  The  diatomaceous  shales 
vary  from  the  fine,  soft,  white,  cTiallrv  form  to  the  hard,  brittle,  flinty 
variety,  which  has  been  altered  to  this  form  by  silica-bearing  waters. 
In  general  the  soft  chalky  form  is  thick-bedded  and  breaks  up  into  small 
thin  flakes,  while  the  flinty  form  is  found  in  narrow  ribbon-like  beds 
about  2"  in  width.  The  microscope  shows  that  all  varieties  contain 
abundant  organic  remains  and  a  chemical  examination  shows  they  are 
composed  chiefly  of  silica.  The  color  varies  from  white  to  brown.  The 
shales  are  on  the  whole,  rather  brittle  and  fracture  and  fold  easily,  giv- 
ing rise  to  many  small  minor  folds  in  the  formation,  which  often  com- 
plicates and  confuses  the  nature  of  the  real  .structure.  Characteristic 
fossils  are  TurritcUa  oco}jn)>a  and  Pccten  pecJiliami. 

The  Monterey  shale  formation  is  very  widespread  in  the  Coast 
Ranges,  occuring  as  far  north  as  Point  Arena,  Mendocino  County,  and 
as  far  south  as  the  Orange  and  San  Diego  County  line. 

The  principal  localities  are  (1)  Point  Arena  and  Point  Rej^es. 
Those  two  localities  are  the  only  known  occurrences  north  of  the  Bay 
of  San  Francisco.  (2)  Berkeley  Hills.  (3)  Santa  Cruz  Mountains. 
(4)  Vicinity  of  IMonterey.  (5)  Salinas  Valley,  where  it  ha.s  been  called 
tlie  Salinas  shale.     (6)  San  Luis  Obispo  and  Santa  Barbara  counties. 

(7)  Ventura  County,  where  it  has  been  called  the  Modelo  formation. 

(8)  Los  Angeles  County  where  it  has  been  called  the  Puente  shale. 

(9)  Orange  County.     (10)  Kern  County  where  it  has  been  called  the 
Maricopa  shale. 

*NoTE. — Recent  paleontological  work  has  shown  that  these  so-called  Vaqueros 
sandstones  probably  belong  to  the  upper  portion  of  the  Monterey  series  and  can  be 
classified  as  belonging  to  the  Temblor  formation. 


32  CALIFORNIA   STATE    MINING    BUREAU. 

The  IMonterey  shale  is  the  original  source  of  the  oil  and  underlies 
the  reservoir  beds  in  the  following  fields:  (1)  ^Midway-Sunset  field. 
(2)  Kern  River.  (3)  Los  Angeles  and  Orange  County  fields.  (4)  The 
Ojai,  the  Piru,  the  Santa  Paula  and  Ventura  Avenue  fields  of  Ventura 
County.      (5)  The  Arroyo  Grande  field. 

In  tlie  Santa  I\Iaria  district  the  oil  has  collected  directly  in  the  Mon- 
terey shale,  a  fractured  tiinty  zone  near  the  base  of  the  formation  acting 
as  the  reservoir. 

The  oil  is  black  and  of  an  asphaltic  base  ranging  in  gravity  from 
9°  Haume  in  tlie  Casnialia  field  to  •'^6'^  Baume  in  the  Midway. 

Jt  is  probal)le  tliat  ovei-  60  per  cent  of  the  105.000,000  barrels  of  oil 
produced  in  California  in  1020  liad  its  origin  in  the  ^Monterey  shale 
formation.  IMost  of  this,  however,  has  migrated  to  the  overlying  forma- 
tions and  the  ^lonterey  actually  yielded  only  about  6,000,000  barrels  or 
6  per  cent  of  the  entire  yield  of  tlu'  state. 

The  Santa  Margarita  formation  (upper  Miocene)  consists  of  a  hard 
compact  sandy  diatomaceous  shale  and  a  white  granitic  sandstone 
member. 

In  the  Salinas  Valley  area  the  white  sandstone  is  best  developed  and 
the  diatomaceous  shale  is  only  about  -100  feet  thick.  In  the  San  Joa- 
quin Valley  the  diatomaceous  shale  is  well  developed  and  consists  of 
about  2000  feet  of  hard  compact  blue  shale,  somewhat  more  sandy  than 
the  ^Monterey  diatomaceous  shale.  It  is  found  only  in  the  Middle  Coast 
Ranges  between  the  Salinas  Valley  and  the  San  Joaquin  Valley.  The 
characteristic  fossils  are  Pecten  cra^sicardo  and  Ostrea  titan. 

The  Santa  Margarita  is  oil-bearing  in  the  following  areas.  (1)  Small 
seepages  near  San  Ardo  in  the  Salinas  Valley.  (2)  Small  seepages  in 
the  Park  field  and  Lonoak  districts  of  jMonterey  County.  (3)  Along 
the  west  side  of  the  San  Joaquin  Valley  from  Sunset  to  Devil's  Den, 
where  it  overlies  the  ^Monterey  shale  and  probably  contributes  to  the 
oil  in  the  McKittrick  beds  which  form  the  principal  reservoir  beds  of 
the  west-side  fields.  In  the  Belridge  and  Lost  Hills  fields  oil  has  col- 
lected directly  in  certain  sandy  beds  of  the  Santa  Margarita  shale. 
This  oil  is  rather  light,  averaging  almost  38°  Baume  and  is  commonly 
known  as  brown  shale  oil. 

It  is  roughly  estimated  that  the  Santa  Margarita  yielded  in  the  San 
Joaquin  Valley  almost  2,000,000  barrels  in  1920  or  almost  2  per  cent 
of  the  state's  production. 

The  San  Pablo  formation  consists  of  about  1500  feet  of  a  rather 
coarse,  blue-gray  sandstone,  found  principally  in  the  vicinity  of  San 
Francisco  Bay.  Characteristic  fossils  are  Pecten  crassicardo  and  Pec- 
ten raijmondi.  The  San  Pablo  is  not  known  to  contain  oil,  in  any 
appreciable  amounts. 

Pliocene. 

Formations  of  Pliocene  age  are  the  mo.st  prolific  s;ouree  of  oil  in  the 
state.  This  is  due  to  the.  fact  that  they  overlie  the  diatomaceous  shale 
of  the  ]\Ionterey.  The  lower  portion  of  the  Pliocene  may  be  considered 
as  being  represented  by  the  Fernando  Series  in  Southern  California, 


PETROr-EUM    RESOURCES   OF    CALIFORNIA.  33 

the  McKittrick  trmnp  in  tho  San  Joa(iuin  Valley  and  middle  Coast 
Kange,  and  the  Merced  Serit's  in  Northern  C'alifoi'nia. 

The  upper  Pliocene  may  be  called  the  Saugus  in  Southern  California 
and  the  I'aso  Robles  in  Central  and  Northern  California. 

The  Fernando  is  found  south  of  the  Teliachapi  mountains  and  the 
Santa  ^laria  Kiver.  It  consists  of  soft  blue  shales  and  medium  coarse 
gray  and  white  sands.  Near  the  top  there  are  beds  of  gravel  made 
up  of  well  rounded  crystalline  pebbles.  It  has  a  maximum  thickness 
of  al)OUt  8000  feet.  It  is  best  known  in  the  following  localities:  (1) 
Puente  Hills.  (2)  Vicinity  of  Los  Angeles.  (3)  Southwestern  Ven- 
tura County.     (4)   Santa  Maria  district. 

In  the  following  fields  its  beds  are  the  principal  sources  of  oil. 
(1)  Los  Angeles  and  Orange  county  fields.  (2)  The  Ojai,  Pirn,  Santa 
Panla  and  Ventura  Avenue  fields  of  Ventura  County.  (3)  The  Sum- 
merland  field. 

Characteristic  fossils  of  the  lower  Pliocene  are  Pcclen  owzni  and 
Pecten  Jiralcjji. 

During  the  year  1920  beds  of  Fernando  age  produced  30,500,000  bar- 
rels of  oil  or  30.5  per  cent  of  the  entire  state's  production. 

In  the  San  Joaquin  Valley  beds  equivalent  to  the  Fernando  are  called 
McKittrick  and  consist  of  loose  gray  sands  and  fine  blue  shales.  The 
maxinuun  thickness  is  about  4000  feet.  The  J\IcKittriek  overlies  the 
Monterey  and  Santa  Margarita  shales  in  the  ]\Iidway-Sunset,  IMcKit- 
trick,  Elk  Hills,  Belridge,  Lost  Hills  and  Kern  River  fields  and  con- 
tains the  principal  oil  sands  of  these  fields.  During  the  year  1920 
these  beds  produced  43,800.000  barrels  of  oil  or  43.8  per  cent  of  the 
total  state  production.     The  oil  is  black  and  averages  about  26°  Baume. 

In  the  ]\Iiddle  Coast  Ranges,  beds  equivalent  to  the  McKittrick  and 
Fernando  formations  have  been  called  Etchegoin  and  Jacalitos  and 
consist  of  loose  sands,  gravels  and  bine  shales.  They  contain  no  oil  in 
commercial  quantities. 

In  Northern  California  the  lower  Pliocene  is  called  the  Merced  and 
consists  in  general  of  white  and  gray  sandstone,  conglomerate  and 
muddy  shales.  It  has  a  maximum  thickness  of  about  3000  feet.  It  is 
best  developed  on  the  San  Francisco  Peninsula  and  in  the  Santa  Cruz 
Mountains,  where  it  overlies  the  ]\Ionterey  shale  and  contains  oil  in 
small  quantities  along  the  coast  side  of  the  mountains  between  Santa 
Cruz  and  Ilalfmoon  Bay.     In  this  region  it  is  known  as  the  Pnrisima. 

In  Southern  California  the  uppermost  Pliocene  may  be  called  the 
Saugus  and  consists  of  soft  sands  and  gravels.  It  contains  no  oil  in 
commercial  quantities.  The  division  between  the  Fernando  and  Sau- 
gus is  not  noticeable  excei)t  on  detail  work. 

In  central  and  northern  California  the  loose  sands  and  gravels  of  the 
upper  Pliocene  may  be  called  the  Paso  Robles.  These  beds  contain  no 
oil  in  commercial  quantities. 

Characteristic  fossils  of  the  upper  Pliocene  are  Pecten  hellus  and 
Crepidnla  princcps. 

Plate  II  shows  a  correlation  of  the  oil-bearing  formations  of  Cali- 
fornia from  tlie  Cretaceous  to  the  Pliocene.     This  table  is  not  intended 


-13322 


34  CALIFORNIA    STATE    MINING   BUREAU. 

as  a  complete  correlation  table  of  all  the  Tertiary  formations  of  the 
West  Coast,  but  is  intended  to  correlate  in  a  rough  manner  for  practical 
use  those  formations  wliich  liave  an  influence  upon  the  origin  and  accu- 
imilation  of  petroleum  in  California.^  Formations  from  which  oil  has 
been  produced  in  commercial  quantities  for  an  appreciable  length  of 
time  have  been  printed  in  red. 

Formations  fi'om  which  oil  has  l)een  obtained  in  small  quantities,  but 
not  on  a  commercial  scale,  or  wliicli  contain  authentic  seepages  of  oil, 
have  been  printed  in  green. 

Formations  from  which  there  has  been  no  actual  production  of  oil  or 
which  contain  no  authentic  seepages  of  oil  have  been  printed  in  black. 
These  differentiations  are  based  upon  the  actual  facts  known  to  date. 
It  is  not  intended  that  this  should  condemn  those  formations  which 
have  been  printed  in  black  or  green,  as  it  is  possible  that  future  drill- 
ing might  show  that  they  contain  oil  in  commercial  (juantities. 

'In  preparing  this  table  the  writer  is  indebted  to  Prof.  B.  L.  Clark  of  the  University 
of  California  for  assistance  and  advice. 


PETROLEUM    RESOURCES   OP    CALIFORNIA.  35 


CHAPTER  III. 

Possibilities  of  Oil  in  the  Coast  Area  North  of  the  Bay  of  San 

Francisco. 

(Includes  tlie  counties  of  Marin,   Sonoma.   Mendocino,   Humboldt,   Trinity  and 

Del  Norte.) 

The  general  geofrrapliy  and  geology'  of  this  region  has  been  discussed 
in  Chapter  II.  A.s  stated  there,  the  niajdr  portion  of  this  area  is  cov- 
ered with  cry.stalline  rocks  and  therefore  affords  no  possibility  of  being 
oil  bearing.  The  oil  possibilities  are  limited  to  small  areas  of  sedi- 
mentary rocks  in  the  Sonoma  Valley  and  along  the  ocean  edge  from 
Rolinas  Bay  to  tlie  mouth  of  the  Eel  River. 

As  tile  county  ])onndaries  have  been  made  to  eonfonu  more  or  less  to 
the  topogra{)hical  and  geological  districts  of  this  area,  it  may  best 
be  discussed  in  detail  by  counties. 

Marin   County. 

Marin  County  is  a  rather  rugged  mountain  area  of  529  square  miles. 
Geologically  it  has  been  divided  into  two  areas  by  the  San  Andreas 
Fault,  which  runs  in  a  northwest  direction  from  Bolinas  Bay  to 
Tomales  Bay.  The  country  lying  east  of  tlie  fault,  wliich  is  the  upthrow 
side,  is  called  the  Marin  i)eninsnla  and  comprises  about  three-quarters 
of  the  county.  The  rocks  exposed  are  of  the  Franciscan  formation  of 
Jurassic  age  and  consist  of  beds  of  massive  gray-green  sandstone  and 
radiolarian  chert  which  have  been  intruded  by  masses  of  serjientinc 
and  basalt.  Both  tbe  character  and  age  of  these  beds  preclude  their 
being  oil  bearing  and  this  district  may  be  dismissed  as  having  no  oil 
possibilities. 

The  country  lying  west  of  the  San  Andreas  fault  is  called  the  Point 
Reyes  peninsula  and  as  a  result  of  being  on  the  downthrow  side  of  the 
fault  rocks  of  Miocene  and  Pliocene  age  are  found  exposed  in  this 
district. 

These  formations  consist  of  bituminous  shale  of  the  Monterey  forma- 
tion and  loose  marine  .sands  of  the  ]\Ierced  formation  (lower  Pliocene.) 

The  ]\Ionterey  shales  cover  about  nine-tenths  of  the  peninsula.  In 
the  northern  portion  near  Inverness  and  Tomales  Bay  they  rest  directly 
on  the  granitic  rocks.  At  Bolinas  Point  and  Diixbiiry  Reef  the  shales 
are  distinctly  bituminous  and  there  are  small  seepages  of  heavy  black 
oil  at  both  of  these  localities.  Due  to  the  close  proximity  of  the  shales 
to  the  fault  zone,  they  have  been  intensely  folded  and  crushed,  which 
obscures  the  true  natur(^  of  the  structure.  However,  there  are  at  least 
two  well  defined  anticlines  on  the  peninsula  as  well  as  numerous  minor 
folds.  The  axis  of  the  most  westerly  fold  may  be  seen  along  the  beach 
one-half  mile  west  of  the  town  of  Bolinas  where  it  strikes  N.  30°  W. 
The  axis  of  the  second  fold  runs  along  the  high  ridge  about  one-balf 
mile  west  of  Pine  Gulch  and  Oleina  Creek.  This  strikes  in  a  general 
northwest  direction.  The  total  thickness  of  the  Monterey  in  this  area 
is  about  4000  feet.  The  ]Merced  sands  occupy  a  small  area  in  Paradise 
Valley,  just  north  of  the  town  of  Bolinas.     The  total  thickness  of  these 


36  CALIFORNIA    STATE    MINING   BUREAU. 

sauds  is  about  GOO  feet  and  tlie  general  dip  is  about  30°  to  the  east. 
Ordinaril}-  it  would  be  expected  that  these  sands  would  be  petroliferous, 
as  they  overlie  the  bituminous  shale ;  this  is  not  the  case,  however,  as 
they  show  no  evidence  of  any  oil  content.  This  lack  of  oil  is  probably 
due  to  the  great  unconformity  l)etween  these  beds  and  the  JNIonterey 
shale.  Three  wells  have  been  drilled  just  west  of  the  town  of  Bolinas 
on  tlie  Garzolia  Ranch.  Two  of  these  were  drilled  about  one-fourth  of 
a  mile  west  of  the  ranch  house  at  the  head  of  a  small  gully.  These 
wells  were  drilled  to  a  depth  of  about  1800  feet  in  the  ^Monterey.  The 
one  nearest  the  ranch  house  encountered  no  oil,  the  one  nearest  the 
ocean  had  a  small  showing  at  700  and  1200  feet.  A  third  well  was 
drilled  on  the  sea  cliff  just  back  of  Duxbury  Reef.  This  well  went  into 
the  ^Monterey  for  2800  feet  and  encountered  small  showing  at  200 
and  2400  feet.     These  wells  were  drilled  about  1905. 

The  possibility  of  obtaining  oil  in  commercial  quantities  in  this  dis- 
trict is  not  very  good.  The  upper  ]\Iiocene  sands  which  once  probably 
overlayed  the  IMonterey  shale  and  in  which  the  oil  content  of  the  shales 
probably  collected  have  been  removed  by  erosion.  Such  oil  as  remains 
is  in  small  quantities  in  fractured  zones  in  the  shale  and  it  is  doubtful 
if  anything  more  than  a  showing  would  be  encountered  in  any  well 
drilled  in  this  area.  Fig.  3  shows  a  generalized  east  and  west  section 
through  a  point  about  two  miles  north  of  Bolinas. 

Sonoma  County. 

Sonoma  County  comprises  an  area  of  1577  square  miles.  Three- 
fourths  of  this  area  is  covered  l)y  rocks  of  Franciscan  formation  and 
therefore  cannot  be  considered  as  having  any  oil  possibilities. 

One  area  of  sedimentary  rocks  which  might  possibly  contain  oil,  con- 
sists of  a  narrow  strip  of  the  Cretaceous  formation  which  outcrops 
along  the  coast  from  the  Russian  River  north  to  the  Gualala  River. 
This  strip  of  Cretaceous  is  almost  four  miles  wide  and  rests  on  its 
eastern  edge  on  the  Franciscan.  These  rocks,  which  are  probably  of 
Chico  age,  consist  of  massive  fine-grained  sandstone  and  pebbly  sand- 
stone interbedded  with  fine  dark-colored  muddy  shales.  The  general 
dip  is  about  35°-40°  to  the  west.  On  certain  of  the  wave-cut  terraces 
the  Chico  is  covered  by  terrace  deposits  of  fine  brown  sand.  There  are 
no  known  indications  of  oil  in  this  area,  and  it  cannot  be  considered  as 
having  anj'  possibilities  as  it  contains  neither  favorable  structure  nor 
organic  shales. 

A  second  area  of  sedimentaries  is  around  the  town  of  Valley  Ford, 
where  there  are  about  six  square  miles  of  fine  sands,  clays  and  con- 
glomerates, probably  of  the  Merced  formation  (Lower  Pliocene). 
These  beds  are  lying  directly  on  the  eroded  surface  of  the  Franciscan. 
There  is  nothing  to  indicate  that  these  beds  contain  oil  and  this  area 
can  be  dismissed  as  having  no  possibilities. 

A  third  area  of  sedimentaries  in  Sonoma  Count}'  is  in  the  Sonoma 
Valley.  The  east  and  w^est  side  of  the  valley  is  made  up  mainly  of 
Franciscan  formation  and  Pliocene  lava  flows.  However,  in  the 
center  of  the  valley  there  is  a  range  of  hills  known  as  the  Sonoma 
Mountains  and  which  extend  from  Santa  Rosa  to  San  Pablo  Bay.  In 
these  hills  there  are  outcrops  of  sedimentary  rocks  of  Tertiary  age, 
which  contain  seepages  of  oil. 


PETROLEUM    RESOURCES   OF    CALIFORNIA. 


37 


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38  CALIFORNIA    STATE    MINING   BUREAU. 

At  the  upper  end  of  these  hills,  near  Santa  Rosa,  tlie  formations 
consist  of  fine  sands  and  clays  of  the  INIerced  (Lower  Pliocene)  which 
are  lying  on  the  Sonoma  tuff  and  ]\[arkwest  and&site  (Lower  Pliocene). 
Beneath  these  lava  Hows  there  is  a  small  thickness  of  San  Pahlo  forma- 
tion which,  in  turn,  rests  upon  the  Franciscan.  There  is  nothing  to 
indicate  that  this  portion  of  the  hills  contains  oil. 

At  the  south  end  of  the  hills,  between  the  towns  of  Petaluma  and 
Sonoma,  the  formations  consist  of  medium  coarse  blue  sands  and  fine 
sandy  shales,  pro])ably  of  the  San  Pablo  formation,  which  are  dipping 
at  an  angle  of  about  35°  to  the  southeast;  on  their  western  edge  these 
beds  probably  rest  ui)on  tlie  Franciscan  beneath  Petaluma  Creek.  The 
contact,  however,  is  obscured  by  overlying  beds  of  Pliocene  tuff  and 
lava.  The  eastern  edge  of  these  San  Pablo  beds,  near  the  town  of 
Sonoma,  is  also  covered  by  volcanics,  which  are  dipping  at  about  20° 
to  the  east.  On  the  hills  east  of  the  town  of  Sonoma,  the  dip  changes 
and  the  Sonoma  tuff  and  ^larkwest  andesite  are  found  dipping  at  an 
angle  of  about  30°  to  the  west.  Overlying  these  lavas  is  a  small  thick- 
ness of  INIerced  sands  and  conglomerates.  Near  the  Sonoma-Napa 
County  boundary  line,  the  S:in  Pablo  beds  again  appear,  this  time 
dipping  30^  to  the  west,  indicating  tliat  there  is  a  syncline  in  the  valley 
south  of  the  town  of  Sonoma.  East  of  the  Sonoma-Napa  l)oundary, 
the  San  Pablo  beds  rest  unconformably  upon  a  massive  buff'  sandstone, 
prol)ably  of  Tejon  age,  which  is  dipping  at  about  70°  to  the  east. 

Evidence  as  to  petroleum  is  as  follows :  On  the  Ducker  ranch,  three 
and  one-half  miles  east  of  Petaluma  and  one  and  one-half  miles  east  of 
the  old  adobe  fort,  in  the  bottom  of  a  small  canyon,  there  are  seepages 
of  a  hea\y  black  asphaltic  oil  in  the  blue  sands  of  the  San  Pablo 
formation.  These  beds  are  apparently  dipping  at  an  angle  of  about 
40°  to  the  southeast.  About  1909,  four  wells  were  drilled  on  the  mesa 
just  above  the  seepages.  The  Ramona  Oil  Company  drilled  three  of 
the  wells  and  the  Petaluma  Home  Oil  Company,  one  well.  These  holes 
have  now  been  a])andoned.  AVell  No.  1  of  the  Ramona  Oil  Company 
was  drilled  in  blue  clay  and  })rown  sand  to  a  depth  of  800  feet,  where 
it  is  claimed  that  gas  was  struck,  which  had  a  pressure  of  217  pounds 
and  a  flow  of  690,000  cubic  feet  per  24  hours.  The  well,  however,  soon 
clogged  up  and  the  flow  ceased. 

Well  No.  2  was  drilled  to  a  depth  of  910  feet,  logging  oil  sands  at 
335  to  400  feet.  In  none  of  these  wells,  however,  was  oil  obtained  in 
commercial  quantities. 

The  origin  of  this  oil  which  is  found  in  the  San  Pablo  l)eds  is  noi 
clear.  There  are  no  known  outcrops  of  ^Tonterey  shale  in  this  district. 
South  of  San  Pablo  Pay,  however,  in  Contra  Costa  County,  there  is 
quite  an  area  of  bituminous  shale  of  the  IMonterey.  Tt  is  po.ssible  that 
this  shale  is  present  beneath  San  Pablo  Bay,  and  the  San  Pablo  sand- 
stone Avhich  is  dipping  to  the  southeast  may  be  in  contact  with  these 
bituminous  sludes,  beneath  the  waters  of  the  bay.  Tn  that  case,  the 
oil  content  of  the  shales  would  tend  to  niove  up  the  dip  into  the  porous 
sands  of  the  San  Pablo  formation  and  appear  in  seepages  along  the 
outcrop  of  this  formation.  It  is  the  opinion  of  the  writer  that  the 
structural  conditions  are  not  favorable  for  the  accumulation  of  oil  in 
appreciable  amounts  in  this  area. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  39 

Mendocino   County. 

Mendocino  County  lias  an  area  of  3453  square  miles,  the  major 
portion  of  which  is  rugged  and  mountainous.  The  sedimentary  rocks 
are  confined  to  a  sti-ip  along  the  ocean  edge  and  small  isolated  areas  in 
the  valley  of  the  Eel  Kiver.  The  remainder  of  the  country  is  covered 
with  metamorphic  rocks  of  the  Franciscan  formation  and  can  be  listed 
as  unfavorable  for  oil.  The  strip  along  the  coast  averages  about  eleven 
miles  in  width  from  east  to  west  and  covers  the  entire  sixty  miles  of 
ocean  frontage  of  the  county  in  a  north  and  south  direction.  The 
northern  portion  of  this  strip,  from  the  Humboldt  County  line,  as  far 
south  as  tlie  Garcia  River,  is  composed  of  rocks  of  the  Chico  formation. 
These  beds  consist  of  massive  gray  sandstones  and  fine  dark-colored 
shales.  In  some  places  tlie.se  shales  have  a  .slatey  appearance.  The  forma- 
tions have  been  much  deformed  and  crushed  and  good  dips  are  difficult 
to  obtain.  In  general  the  beds  lie  in  a  monocline,  dipping  about  35° 
to  the  west.  There  is  no  known  indication  of  petroleum  in  this  area 
of  Chico  and  both  structural  conditions  and  the  character  of  tlie  rocks 
are  unfavorable  for  the  accumulation  of  oil. 

In  the  vicinity  of  Point  Arena,  the  Chico  is  overlayed  by  bituminous 
shales  and  some  sandstone  of  what  is  probably  the  INIonterey  formation. 
This  area  of  Monterey  covers  about  25  square  miles.  Its  northern 
boundary  is  marked  by  Alder  Creek,  where  the  shales  are  lying  uncon- 
formably  upon  the  Chico.  The  eastern  boundary  is  along  the  Garcia 
River,  Avhere  the  Monterey  has  been  faulted  against  the  Chico  by  the 
San  Andreas  fault.  The  southern  boundary  is  found  about  2^  miles 
south  of  the  town  of  Point  Arena,  where  there  is  apparently  a  fault 
contact  between  the  Monterey  and  the  underlying  Chico  sandstones. 
Plate  III  is  a  reconnaissance  map  of  this  area,  showing  structure  and 
areal  geology. 

The  Monterey  formation  is  at  least  5000  feet  thick,  the  major  por- 
tion of  which  consists  of  diatomaceous  shale,  of  both  the  flinty  and 
chalky  varieties.  In  the  upper  20C0  feet  there  are  numerous  leuse,s  of 
fine-grained  sandstone.  In  the  lower  TOGO  feet  there  are  two  well  defined 
beds  of  medium  coarse-grained  sandstone.  These  beds  are  about  150 
feet  thick.     The  general  trend  of  the  formation  is  N.  45°  "W. 

Three  well  defined  folds  are  found  within  this  area  of  Monterey. 
The  most  easterly  is  north  of  the  Garcia  River  and  runs  through  the 
town  of  Manchester.  The  sandstone  beds  of  the  lower  portion  of  the 
]\ronterey  are  exposed  along  this  fold. 

The  second  fold  is  found  running  through  the  town  of  Point  Arena. 
The  third  and  last  fold  is  found  close  to  the  beach,  running  N.  45°  W., 
through  the  center  of  Sec.  10,  T.  12  N..  R.  17  W.,  U.  D.  B.  and  M.  As  this 
fold  crosses  a  portion  of  the  O'Neal  Ranch,  it  will  be  designated  as  the 
O'Neal  anticline.  In  general  these  folds  are  rather  narrow  and  steep, 
the  dips  ranging  from  20°  to  60°. 

Indications  of  petroleum  are  as  follows :  Along  the  sea  cliffs,  from  the 
port  of  Point  Arena  as  far  north  as  the  lighthouse,  there  are  numerous 
seepages  of  dark  asphaltic  oil  coming  from  fractured  areas  in  the  dia- 
tornaceous  shale.  Along  the  eastern  flank  of  the  syncline,  correspond- 
ing to  the  O'Neal  anticline  and  just  southwest  of  the  O'Neal  ranch 
house,  there  is  an  outcrop  of  fine-grained  bituminous  sand  about  ten 


40  CALIFORNIA    STATE    MINING   BUREAU. 

feet  thick  which  can  be  followed  in  a  northwest  direction  for  3^ 
miles,  finally  ending  in  the  sea  cliff,  just  east  of  the  lighthouse.  The 
sand  is  heavily  bituminized  and  smells  strongly  of  gasoline.  It  is 
possible  that  this  deposit  might  be  mined  and  distilled  at  a  profit. 

The  following  wells  have  been  drilled  in  this  disti'ict :  The  Mendo- 
cino Coast  Oil  Companv  drilled  a  well,  called  the  Robbins  well,  at  the 
northwest  corner  of  Sec.  11,  T.  12  N.,  R.  17  W.  A  depth  of  2240  feet 
in  Monterey  shale  was  reached,  and  it  is  claimed  that  good  showings 
were  found.  On  the  Hunter  Ranch,  near  the  center  of  Sec.  11,  T.  12 
N.,  R.  12  W.,  a  well  was  drilled  by  a  Fresno  company  and  called  the 
John  D  well.  It  reached  a  depth  of  1700  feet.  The  Robbins  well  was 
drilled  in  1905,  and  the  John  D.  well  in  1910.  Both  wells  are  located 
in  a  syneline  and  can  not  be  considered  as  testing  out  this  district.  In 
1918,  Brandenstein  and  Silverberg  drilled  a  well  about  150  feet  east  and 
north  of  where  the  west  line  of  section  eleven  runs  into  the  ocean.  This 
well  was  located  on  the  axis  of  the  O'Neal  anticline.  A  depth  of  780 
feet  was  reached  and  tar  sands  were  logged  from  522-715.  This  hole 
was  not  drilled  deep  enough  to  be  a  fair  test  of  this  area. 

The  most  favorable  area  for  drilling  in  this  district  consists  of  about 
400  acres  in  sections  10  and  11,  T.  12  N.,  R.  17  W.,  M.  D.  B.  and  M. 
This  area  is  on  the  axis  of  the  O'Neal  anticline.  The  structure  is 
favorable  and  there  is  also  the  possibility  of  a  drainage  area  from  under 
the  ocean.  Seepages  indicate  that  the  fold  contains  some  oil ;  l)ut 
whether  or  not  it  is  in  commercial  quantities  can  only  be  told  by  drilling. 

The  other  areas  of  sedimentary  rocks  in  Mendocino  County  are  along 
the  Eel  River  in  the  vicinity  of  Round  Valley,  Laytonville  and  AVillits. 
These  beds  consist  of  shale  and  sandstone  and  are  found  in  small  isolated 
patches  on  the  Franciscan.  In  general  they  vary  from  100  to  500  feet 
in  thickness  and  cover  areas  of  not  more  than  four  or  five  square  miles. 
Small  seams  of  coal  are  found  in  these  beds  and  the  age  is  probabl}'' 
Eocene.     There  is  nothing  to  indicate  that  they  contain  oil. 

Humboldt  County. 

The  only  area  in  Humboldt  County  that  is  worthy  of  consideration  as 
a  possible  oil  field,  consists  of  a  body  of  sedimentary  rock  which  lies 
along  the  coast  from  the  Mendocino  County  line  to  a  point  about  twelve 
milas  north  of  Eureka.  The  east  boundary  is  marked  in  the  southeast 
by  the  south  fork  of  Eel  River  and  in  the  northeast  by  a  line  about  six 
miles  west  of  Mad  River. 

The  remainder  of  the  county  is  covered  by  the  following  formations : 
(1)  An  area  of  Franciscan  sandstone,  chert  and  serpentine  lies  east 
of  the  sedimentaries  above  mentioned  and  covers  an  area  ot  aboui 
twelve  miles  in  Avidth,  running  in  a  northwest  direction  across  the  center 
of  the  county  from  the  IMendocino  County  line  to  a  point  on  the  coast 
near  Trinidad.  (2)  Immediately  east  of  the  Franciscan,  and  parallel 
to  it,  is  an  area  of  the  Knoxville  (Cretaceous)  formation,  occupying 
an  area  about  four  miles  in  width  and  stretching  in  a  northwesterly 
direction  from  a  point  where  the  Van  Dusen  River  crosses  the  Trinity 
County  line  to  a  point  on  the  coast  near  Big  Lagoon.  (3)  The  north- 
eastern portion  of  the  county,  east  of  the  Knoxville  area,  consists  of 
limestones,  schi.sts  and  slates  of  Paleozoic  age,  together  with  some 
granite. 


PETROLEUM    RESOURCES   OF    CALFPORNIA.  41 

None  of  the  three  above-mentioned  areas  contains  any  evidence  of  oil 
or  others  any  inducement  for  drilling  from  a  geological  standpoint. 

In  the  sedimentary  area  along  the  coast  between  Eureka  and  the 
Mendocino  County  line,  tliere  are  numerous  indications  that  the  forma- 
tions contain  oil,  at  least  in  a  limited  anumnt.  This  area  will,  therefore, 
be  discussed  somewhat  in  detail.  For  the  purpose  of  discussion,  it  can 
best  be  divided  into  two  districts. 

First — That  area  lying  at  the  mouth  of  Eel  River  and  stretching 
appro.ximately  from  Ferndale  to  McKinleyville,  which  may  be  con- 
sidered as  the  flood  plane  which  the  river  has  cut  in  the  soft  Pliocene 
beds  Avhich  are  found  outcro])])ing  here.  On  the  north  flank  of  Bear 
Kiver  Ridge  and  just  south  of  the  town  of  Ferndale  the  best  outcrops 
are  found.  Here  there  is  a  thickm  ss  of  over  5000  feet  of  soft  muddy- 
clay  shales  and  fine-grained  wliite  sandstone,  striking  approximately  a 
little  north  of  west  and  dipping  on  an  average  of  20°  to  the  northeast. 
These  beds  are  known  as  the  Wildcat  Series  and  are  believed  to  be  of 
Pliocene  age,  although  it  is  possible  that  the  lower  beds  may  be  of 
Miocene  or  even  Eocene  age.  They  are  resting  unconformably  upon 
the  underlying  massive  Cretaceous  sandstone.  North  of  the  Eel  River 
the  same  ])eds  are  found  dipping  to  the  southwest  and  it  is  evident  that, 
structurally,  the  valley  of  the  Eel  River  at  its  mouth  is  a  synclinal 
trough,  the  axis  of  which  runs  through  the  town  of  Fortuna,  striking 
a  little  north  of  Avest.  In  the  vicinity  of  Eureka,  the  Wildcat  beds  are 
apparently  dipping  to  the  west  and  it  is  possible  that  small  folds  are 
present  in  this  vicinity.  At  various  times  oil  and  gas  have  been  reported 
as  being  present  in  water  wells  drilled  in  this  district.  The  writer, 
however,  found  no  see])ages  or  indications  of  petroleum  gas. 

The  possibilities  of  this  district  as  an  oil  field  depend  upon  whether 
there  are  favorable  folds,  and  the  presence  of  organic  shale  at  a  reason- 
able depth  beneath  the  Wildcat  beds.  Apparently  both  of  these  factors 
are  lacking,  although  it  is  possible  that  a  more  detailed  survey  might 
find  evidence  of  their  presence. 

Second — This  district  comprises  that  area  lying  approximately  south 
and  west  of  the  Eel  River.  Indications  of  petroleum  eonsisi  of  a  series 
of  seepages  of  light  oil  running  in  a  line  from  the  town  of  Briceland 
to  Capetown,  a  distance  of  nearly  forty-five  miles.  The  territory  that 
can  be  considered  as  offering  any  possibilities  consists  of  the  counuT 
drained  by  the  Bear  and  Mattole  rivers  and  the  district  around  Briceland. 

The  formations  exposed  consist  of  a  lowermost  member  of  massive 
blue-gray  sandstone  of  medium-grained  texture,  interbedded  with  dark 
fine-graineJ  slatey  shales.  Stratagraphically  above  this  is  found  a 
body  of  about  2000  feet  of  dark,  fine-grained  greasy  carbonaceous  shales, 
in  which  are  found  the  seepages  of  oil.  Interbedded  with  the  shale  are 
beds  of  blue-gray  sandstone.  The  last  and  uppermost  member  of  the 
series  consists  of  about  500  feet  of  massive,  hard  blue  sandstone.  This 
series  of  beds  is  probably  of  Chico  (Cretaceous)  age.  They  rest  uncon- 
fonnably  on  their  eastern  edge  along  the  valley  of  the  Eel  River  on  the 
eroded  surface  of  the  Franciscan.  Overlying  the  Chico,  are  small  areas 
of  soft,  fine,  white  sandstone  and  fine,  blue  muddy  shales  and  some 
pebbly  sandstone.  These  beds  are  found  in  the  vicinity  of  Garberville, 
Briceland,  and  the  mouth  of  the  Bear  River  and  are  probably  of  Ter- 
tiary age. 


42  CALIFORNIA    STATE   MINING   BUREAU. 

The  petroleum  found  probably  originated  in  the  carbonaceous  shales 
of  the  Chico  and  has  collected  in  the  interbedded  sandstone  beds.  Any 
production  must  come  from  this  member  of  the  Chico.  The  locations 
of  the  line  of  .seepages  and  the  wells  drilled  are  shown  on  Plate  IV.  The 
oil  is  of  a  paraffine  base,  varying  from  light  green  to  amber  in  color 
and  from  30°  Baume  to  50°  Baume  in  gravity. 

The  topography  consists  of  a  series  of  ridges  and  narrow  valleys, 
having  a  trend  of  N.  45°  W.,  the  elevation  of  the  ridges  being  about 
2500  feet. 

Faulting  is  common  and  the  valley  of  the  Mattole  River  is  probably 
a  structural  valley  formed  by  the  San  Andreas  fault.  The  massive 
sandstone  and  the  soft  shales  of  the  Chico  do  not  contain  well  defined 
bedding  planes  and  good  dips  are  rare.  No  detailed  mapping  was  made 
of  the  structure,  but  in  general  there  are  a  number  of  anticlinal  and 
synclinal  folds  striking  in  a  northwest-southeast  direction,  the  axis  of 
the  anticlines  being  marked  by  the  narrow  valleys  and  the  synclines  by 
the  ridges.  Along  all  the  anticlinal  axes  erosion  has  cut  down  to  the 
lowermost  sandstone  member  of  the  Chico  and  in  no  case  was  a  fold 
found  which  contained  on  its  axis  the  oil  bearing  shale  member  of  the 
Chico.  Hence  any  well  which  would  penetrate  the  oil  sands  must  be 
located  down  the  flanks  of  the  folds,  a  location  which  is  not  generally 
considered  favorable. 

Following  is  a  list  of  the  welLs  drilled,  with  the  reported  results. 
(Located  on  Plate  IV;  map  of  southwestern  Humboldt  County.) 

Year  1865. 

Three  wells  were  drilled  on  Oil  Creek,  marked  on  Plate  IV  as  1-2-3. 
Depth  of  these  wells  is  unknown;  it  is  reported  that  gas  was  found. 
"Well  1  is  in  Sec.  35,  T.  2  N.,  R.  3  W.  Well  2  is  in  Sec.  1,  T.  1  N.,  R.  3  W. 
Well  3  is  in  Sec.  6,  T.  1  K,  R.  2  W. 

Two  wells  on  Bear  Creek,  marked  4-5.  Depth  unknown ;  encountered 
gas  and  a  little  oil.  Well  4  is  in  Sec.  24,  T.  1  N.,  R.  3  W.  Well  5  is  in 
Sec.  20,  T.  1  N.,  R.  2  W. 

McNutt  Gulch  well,  located  in  Sec.  30.  T  1  S.,  R.  2  W.  Depth  300 
feet ;  a  little  oil  found ;  is  still  seeping.     INIarked  6  on  Plate  IV. 

Union  well  on  the  north  fork  of  the  Mattole,  in  Sec.  30,  T.  1  S.,  R.  1 
W.,  marked  7.     Depth  500  feet ;  reported  as  a  fifteen-barrel  well. 

Brown  and  Knowles  well,  in  See.  25,  T.  1  S.,  R.  2  W.,  marked  8. 
Depth  300  feet ;  oil  reported  at  150  feet. 

The  Joel  Flat  well,  known  as  the  Henderson  well,  in  Sec.  15,  T.  1  S., 
R.  2  W..  marked  9.  Depth  500  feet ;  reported  as  a  ten-barrel  well,  and 
300  barrels  of  oil  are  reported  as  being  sold. 

Year  1891. 

Well  on  Buckeye  Creek,  in  Sec.  5,  T.  2  S.,  R.  1  W.,  marked  10. 
Depth  800  feet.  '  Five-barrel  well  reported  at  500  feet.  Tliis  well 
drilled  by  Far  West  Company  and  known  as  the  Burrows  well. 

AVell  on  Buckeye  Creek,  known  as  the  Humboldt  well,  in  Sec.  6,  T.  2 
S..  R.  1  W.,  marked  11.     Depth  1900  feet;  little  oil. 

Davis  Creek  well,  in  Sec.  13,  T.  1  S..  R.  3  W.,  marked  12.  Drilled  by 
Far  West  Company;  depth  800  feet;  little  oil. 


petroleum  resources  of  california.  43 

Years  1901-1902. 

Mcintosh  well  on  Zanona  Rancli,  in  See.  29,  T.  1  S.,  R.  2  W.,  marked 
13      Depth  1700  feet.     Reported  as  a  fifteen-barrel  well. 

Wild  Goose  well,  in  Sec.  15,  T.  1  S.,  R.  2  W.,  marked  U:  Depth 
1003  feet :  oil  encountered  at  221,  420  and  775  feet ;  reported  as  a  fifteen- 
barrel  well.  ^ 

Craig  well  on  the  North  Fork  of  the  ^Mattole,  in  Sec.  30,  T.  1  b., 
R.  1  W°.  marked  15.     Drilled  to  800  feet ;  strong  showing  of  oil  and  gas 

reported. 

Iloaglin  well  in  the  upper  :Mattole,  in  Sec.  1,  T.  3  S.,  R.  1  W.,  marked 
16.     Depth  1800  feet ;  showing  of  oil  reported. 

Well  at  Brieeland,  in  Sec.  18,  T.  4  S.,  R.  3  E.,  marked  17.  Drilled 
to  780  feet;  has  been  producing  enough  gas  for  20  years  to  supply 
store  and  hotel. 

Year  1908. 

:\rcWherter  well  on  Bear  Creek,  Sec.  14,  T.  1  N.,  R.  3  W..  marked  18. 
Depth  unknown  ;  reported  showing  of  oil  and  gas. 

Brieeland  Oil  and  Laud  Co..  See.  33.  T.  4  S.,  R.  4  E.,  marked  19. 
Drilled  to  2100  feet ;  little  oil  at  410,  and  granite  encountered  from  503 
to  2100  feet. 

Years  1920-1921. 

Humboldt  Oil  Company  now  drilling  in  Sec.  20,  T.  4  S.,  R.  3  E., 
marked  20. 

Northern  Counties  Oil  Company  now  drilling  in  Sec.  36,  T.  2  S.,  R.  1 
W.,  marked  21. 

All  townships  and  ranges  refer  to  Humboldt  Meridian. 

In  regard  to  the  reported  amount  of  oil  produced  at  the  various  wells, 
as  far  as  the  writer  was  able  to  ascertain,  these  figures  are  not  based 
upon  any  accurate  guage.  as  none  of  the  wells  produced  for  any  length 
of  time  and  they  merely  represent  a  guess  on  the  part  of  the  operator 
and  therefore  can  not  be  relied  upon  to  any  extent. 

Possibilities. 

While  a  large  number  of  wells  have  been  drilled  in  this  district,  the 
majority  without  any  definite  results  and  a  few  successful  in  a  small 
way  for  a  limited  length  of  time,  the  results  can  not  be  taken  as  a  fair 
test,  as  methods  of  drilling  and  producing  have  improved  and  changed 
since  the  last  of  these  wells  were  bored. 

The  geological  conditions  in  general  and  the  structure  in  particular 
are  not  favorable  for  the  accumulation  of  oil  in  large  quantities.  How- 
ever, the  district  along  the  Bear  and  ]\lattole  rivers  and  the  area 
around  Brieeland  appear  worthy  of  further  examination  and  testing, 
but  any  drilling  undertaken  should  be  with  the  understanding  that  the 
best  Dossible  return  will  be  small.* 


"A  report   on  the  oil   po.ssil)ilitif'S  of  tliis   rortion   of  Humboldt   County,  by   Mr.   W. 
Stalder,  can  be  found  in  Bulletin  69,  California  State  Mining  Bureau, 


44  CALIFORNIA    STATE   MINING   BUREAU. 

Del    Norte  County. 

Del  Norte  County  is  almost  entirely  covered  with  crystalline  and 
metamorphic  rocks.  The  center  of  the  county  is  occupied  by  crystal- 
line limestones,  slates  and  schists  of  Paleozoic  age.  Along  the  coast 
and  also  on  the  eastern  border  of  the  county  there  are  outcrops  of 
Franciscan  sandstone,  chert  and  serpentine.  In  the  extreme  north- 
west there  is  an  area  of  granite,  all  of  which  are  unfavorable  for  the 
presence  of  oil. 

The  only  areas  of  sedimentary  roclcs  of  sufficient  area  to  be  mapped 
lie  on  the  coast  about  three  miles  north  of  Crescent  City.  Here  there 
is  a  thickness  of  about  700  feet  of  fine-grained,  muddy,  blue  shales,  occu- 
pying an  area  of  about  10  square  miles.  On  all  sides  the  shales  are 
lying  on  the  eroded  surface  of  the  Franciscan.  Fossil  evidences 
indicate  that  the  beds  are  of  Pliocene  age  and  probably  belong  to  the 
Wildcat  Series.  Evidences  of  oil  have  been  reported  from  time  to 
time.  The  writer,  however,  could  find  nothing  that  indicated  the 
presence  of  petroleum.  In  the  middle  of  this  area  on  Sec.  24,  T.  16 
N.,  R.  2  E.,  the  North  Coast  Oil  and  Refining  Company  is  drilling  a  well. 
All  geological  conditions  are  distinctly  unfavorable  for  the  presence  of 
oil  in  Del  Norte  County. 

Trinity  County. 

From  a  geological  standpoint  there  is  nothing  to  indicate  that  oil  will 
ever  be  found  in  Trinity  County.  Formations  exposed  consist  of  highly 
metamorphozed  sediments  of  Paleozoic  age,  some  of  which  have  been 
identified  as  belonging  to  the  Carboniferous  and  Devonian  periods. 
Beneath  these  are  found  crystalline  schists  and  gneisses  which  may  be 
pre-Cambrian.  Large  masses  of  granite  are  common.  The  only  area 
of  sedimentary  rocks  which  has  not  been  metamorphosed  to  a  crystal- 
line condition  is  a  small  strip  of  Knoxville  shale  in  the  southwestern 
portion  of  the  county,  a  continuation  of  the  Knoxville  area  in  Humboldt 
County.  There  is  no  authentic  record  of  any  indication  of  petroleum 
in  the  county. 


PETROLEUM    RESOURCES   OP    CALIFORNIA.  45 


CHAPTER  IV. 
Oil  Possibilities  in  Northeastern  California. 

(Consists  of  the  Counties  of  Siskiyou.  Modoc,  Shasta  and  Lassen.) 

The  western  portion  of  this  region  includes  the  di.striet  of  the  Siski- 
you Mountains  and  the  ea.stern  portion,  the  district  of  the  Lava  Beds. 

Topographically  and  geologically  this  territory  lends  itself  to  he 
discussed  by  counties, 

Siskiyou    County. 

The  main  line  of  the  Southern  Pacific  Railroad  from  San  Francisco 
to  Seattle  divides  the  county  into  approximately  two  parts.  West  of 
the  line  of  the  railroad  the  county  is  extremely  nigged  and  mountainous 
and  is  known  as  the  region  of  the  Siskiyou  Mountains.  The  formations 
exposed  are  highly  metamorphosed  sediments  of  Paleozoic  and  possibly 
pre-Cambrian  age,  together  with  large  masses  of  granite,  all  unfavorable 
for  containing  oil. 

East  of  the  line  of  the  railroad  is  a  great  lava  plateau,  stretching 
eastward  to  the  Modoc  County  line.  From  the  plateau  rise  various  vol- 
canic peaks  to  heights  of  5000  to  8000  feet  and  in  the  south-central  por- 
tion, ]\rount  Sha.sta  towers  at  a  height  of  14,380  feet.  This  region,  with 
some  minor  exceptions,  which  will  be  noted  below,  is  entirely  covered 
by  lava  flows,  chiefly  andesites  and  basalts.  The  age  of  the  lava  is 
thought  to  be  Tertiary  with  some  Quaternary  flows  near  IMount  Shasta. 
No  oil  can  be  expected  from  the  lava  beds.  Whether  or  not  they  cover 
Tertiary  formations  which  might  contain  oil  can  not  be  told  from  sur- 
face indications.  In  the  upper  valley  of  the  Little  Shasta  River,  about 
six  miles  southeast  of  ^Montague,  there  are  some  fresh-water  springs  in 
the  lava  beds  from  which  bubbles  of  gas  are  coming.  These  so-called 
gas  springs  have  caused  considerable  oil  excitement  in  this  region.  An 
examination  convinced  the  writer  that  the  gas  is  in  no  way  connected 
with  petroleum  deposits. 

LTnmetamorphosed  sedimentary  areas  are  found  in  the  following 
localities:  (1)  A  small  area  of  Chieo  (Cretaceous)  running  from  the 
vicinity  of  Round  Mountain  north  through  Hornbrook  to  the  Oregon 
line  at  Hilts.  The  Chico  consists  of  about  1500  feet  of  massive  sand- 
stones and  thin-bedded  dark  shales.  The  beds  have  a  dip  of  15°  to  the 
east  and  strike  N.  40°  AV.  They  contain  no  evidence  of  petroleum. 
Overlying  the  Chico  on  the  east  is  a  small  area  of  fine-grained  green 
sandstone  and  sandy  shale  containing  seams  of  lignite,  in  the  vicinity 
of  Ager.  This  formation  is  proliably  of  Eocene  age.  It  occupies  an 
area  about  18  miles  long  and  10  miles  wide  and  has  a  dip  of  20°  to  the 
east,  where  it  rests  against  the  lava  beds.  Its  exact  relationship  to  the 
lavas  is  not  clear.  No  evidences  of  oil  were  found  in  this  formation.  (2) 
A  second  area  of  sedimentaries  is  found  just  east  of  Dunsmuir,  along  the 
valley  of  the  McCloud  River.  The  formations  consist  of  more  or  less 
altered  shales,  sandstone  and  limestone  of  Carboniferous,  Devonian 
and  Jurassic  age.     They  contain  no  evidence  of  petroleum. 


46  CALIFORNIA    STATE   MINING   BUREAU. 

Modoc   County. 

Modoc  County,  lying  in  the  extreme  northeastern  portion  of  the  state, 
consists  of  a  high  plateau  with  an  average  elevation  of  nearly  5000  feet, 
from  which  detached  mountain  peaks  and  volcanic  ranges  rise  to  a 
height  of  8OU0  and  9000  feet.  Along  the  northern  and  eastern  border 
there  are  large  fresh-water  lakes.  The  formations  that  outcrop  consist, 
with  some  minor  exceptions,  of  flat-lying  lava  beds,  chiefly  andesite 
and  basalts,  the  age  of  which  is  probal)ly  Tertiary.  There  is  no  sur- 
face evidence  as  to  what  underlies  tlie  lavas,  or  what  is  their  total 
thickness.  A  few  miles  south  of  Fall  River  Mills,  Shasta  County,  the  Pit 
River  has  cut  its  channel  down  18(X)  feet  in  these  fiat-lying  beds,  and 
there  is  no  evidence  of  any  underlying  formations. 

Running  from  a  point  on  the  Pit  River,  about  seven  miles  west  of 
Canby  and  as  far  east  as  Alturas  and  as  far  north  as  Goose  Lake,  is  a 
flat-lying  bed  of  fresh  water  diatomaceous  shale,  varying  from  25  to 
50  feet  in  thickness.  The  .shale  is  interbedded  between  two  lava  flows 
and  has  a  small  caping  of  muddy  shale.  The  deposit  probably  repre- 
sents a  Pleistocene  lake  bed.  The  thickness  of  shale  is  too  small  to 
form  any  appreciable  amount  of  petroleum  and  also  there  is  lack  of 
structure.     Modoc  County  offers  no  inducements  for  drilling  operations. 

Shasta  County. 

Geologically,  Shasta  County  may  be  divided  into  three  districts: 
(1)  The  eastern  half  of  the  county,  lying  approximately  east  of  the 
122°  meridian,  is  topographically  similar  to  IModoc  County.  It  is 
covered  with  the  same  lava  flows  and  is  likewise  unfavorable  for  the 
development  of  petroleum.  (2)  The  northwestern  portion  of  the  county, 
lying  approximately  west  of  122°  meridian  and  north  of  Redding, 
is  a  rugged,  mountainous  region.  The  formations  consist  of  l)eds  of 
limestone,  chert,  slate,  sandstone  and  conglomerate,  all  more  or  less 
metamorphosed  and  belonging  to  the  Devonian,  Carboniferous,  Trias- 
sic,  and  Jurassic  periods.  There  are  also  masses  of  intrusive  granite 
and  serpentine.  The  count}^  has  been  much  deformed  and  crushed 
and  the  beds  are  steeply  tilted.  This  area  has  been  mapped  in  detail 
and  the  report  published  by  the  U.  S.  Geological  Survey,^  so  no  further 
description  of  the  formations  will  be  given  here.  While  formations 
similar  to  the  Devonian,  Carboniferous,  and  Triassic  limestone  found 
outcropping  in  this  area  produce  oil  in  other  regions  of  the  United  States, 
no  evidence  of  petroleum  has  been  found  in  this  area,  nor  is  their  struc- 
ture favorable  for  its  accumulation.  (3)  The  extreme  southwestern 
portion  of  the  county  and  the  area  around  the  head  of  the  Sacramento 
Valley  are  covered  by  beds  of  Cretaceous  age.  Tertiary  lava  flows  and 
valley  alluvium.  Beneath  these  sediments  are  masses  of  granite,  ser- 
pentine and  metamorphic  Paleozoic  rocks.  As  this  region  has  been 
described  in  detail  in  the  Redding  Folio,  U.  S.  Geological  Survey,  no 
further  description  of  the  geology  will  be  given  here.  It  suffices  to  say 
that  the  district  contains  no  evidences  of  petroleum  and  is  unfavorable 
for  its  accumulation. 

At  the  head  of  the  Sacramento  Valley,  .just  north  of  Redding,  along 
Buckeye  Creek,  there  are  a  number  of  salt  and  sulphur  springs  in  the 

•Redding  folio  13S.      U.  S.  Geological  Survey. 


PETROLEUM    RESOURCES   OP    CALIFORNIA.  47 

Chico  beds  from  which  small  quantities  of  gas  are  emanating.  On  the 
strength  of  these  so-called  gas  springs,  four  wells  were  drilled,  the 
deepest  being  1000  feet.  They  were  drilled  in  the  Chico  and  probably 
penetrated  to  the  lowerniost  ])eds  of  this  formation.  No  oil  was  encoun- 
tered and  only  a  small  quantity  of  gas.  It  is  the  opinion  of  the  writer 
that  the  gas  found  is  not  connected  with  petroleum  deposits. 

Lassen    County. 

Lassen  County  is  similar  to  Modoc  and  eastern  Shasta  in  topography 
and  geology.  The  formations  exposed  are  i)raetically  flat-lying  beds 
of  lava,  chiefly  andesite  and  basalt.  There  is  nothing  to  indicate  their 
total  thickness,  or  the  character  of  the  underlying  formations,  except 
on  the  south  boundary  of  the  county  where  they  are  lying  on  the  eroded 
surface  of  the  granites  of  the  Sierra  Nevada.  South  and  east  of  AVest- 
wood  there  is  a  tongiu^-like  mass  of  the  Carboniferous  formation  com- 
ing in  from  Plumas  County.  There  are  no  favorable  indications  of 
oil  in  Lassen  County. 


48  CALIFORNIA    STATE    MINING    BUREAU. 

CHAPTER  V. 

Area  of  the  Sierra  Nevada  Mountains. 

(Consists  of  the  following  Counties:  Pliunas,  Siena.  Eastern  Part  of  Butte 
County,  Eastern  Part  of  Yuba  County,  Nevada,  Eastern  Part  of  Placer.  El 
Dorado,  Amador,  Alpine,  Calaveras,  Tuolumne.  Mariposa,  Eastern  Part  of 
Madera,  Eastern  I'arts  of  Fresno  and  Tulare  Counties  and  that  I'art  of  Kern 
County  that  lies  in  the  Sierras.) 

On  the  north  this  province  may  be  considered  as  ending  along  the 
north  line  of  Plumas  County,  where  the  granite  peaks  of  the  Sierra 
give  way  to  the  lava  beds  of  Lassen  County.  The  eastern  edge  is  marked, 
from  Plumas  County  as  far  south  as  ^lono  County,  by  the  boundary 
line  of  California  and  Nevada  and  thence  it  follows  the  west  line  of 
Mono  and  Inyo  counties,  marked  by  the  great  Sierra  fault  line,  through 
eastern  Kern  to  Tejon  Pass,  where  the  Sierra  proper  ends.  The  western 
edge,  in  this  report,  will  be  considered  as  lying  just  east  of  the  foothills 
of  the  Sacramento  and  San  Joaquin  valleys. 

The  Sierra  Nevada  structurally  may  be  considered  as  a  great  fault 
block,  which  is  being  slowly  tilted,  the  eastern  edge,  marked  by  the 
great  fault  scarp,  going  up  and  the  western  edge  along  the  great  central 
valley  acting  as  the  hinge.  The  result  of  this  tilting  has  given  a  gentle 
western  slope  and  a  rather  abrupt  falling  away  on  the  east  towards 
the  desert  of  Nevada. 

The  rock  exposed  can  be  divided  into  two  series:  (1)  The  Bedrock 
series  consists  of  granitic  rocks,  together  with  bodies  of  schists  and 
slates,  which  have  been  produced  by  intense  metamorphism  of  ancient 
sediments  and  igneous  rocks.  The  main  body  of  altered  sediments  is 
known  as  the  Calaveras  formation,  consisting  of  slates,  quartzites  and 
limestones  of  Carboniferous  age  and  the  Mariposa  slates  of  Jurassic 
age.  (2)  The  Super.jaeent  series,  which  overlies  the  Bedrock  series, 
is  made  up  of  beds  of  auriferous  gravel  of  Eocene  and  ^Miocene  age, 
together  with  lava  flows,  chiefly  andesite  and  rhyolite  tuff,  probably  of 
Miocene  age.  Along  the  foothills  there  are  sediments  of  Cretaceous 
and  Tertiaiy  ages.  These,  however,  will  be  considered  as  belonging  to 
the  Sacramento  and  San  Joaquin  Valley  areas  and  will  be  discussed  in 
chapters  relating  to  those  districts. 

The  southern  half  of  the  Sierra  Nevada,  as  far  north  as  Madera  County, 
is  composed  entirely  of  granitic  rocks.  The  central  ana  northern  por- 
tions contain  tlie  altered  sediments  of  the  Bedrock  series,  together  with 
their  associated  granites  and  the  overlying  gravels  and  lavas  of  the 
Superad.jacent  series.  The  total  absence  of  any  of  the  oil-bearing  forma- 
tions and  the  crystalline  and  metamorphie  character  of  the  rocks 
exposed,  make  the  area  of  the  Sierra  Nevada  an  impossible  one  for  the 
origin  or  accumulation  of  petroleum. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  49 


CHAPTER  VI. 

Area  of  the  S.acramento  Valley,  Ixclldixg  the  East  Slope  of  the 
Coast  Ranges  and  the  Foothills  of  the  Sierra  Nevada. 

(Consists  of  the  counties  of  Tehama,  Glenn,  Western  Butte  and  Yuba,   Sutter, 
Colusa,  Lake,   Yolo,   Napa,   Solano,  Western  Placer,   Sacramento.) 

Tliis  area  will  l)e  divided  into  three  districts  and  each  discussed  in 
more  or  less  detail. 

(1)   DISTRICT  OF  THE  WEST  SIDE  OF  THE  VALLEY  AND   EAST 
SLOPE  OF  THE  COAST  RANGES. 

TOPOGRAPHY. 

Along  the  west  side  the  l^at-lying  lands  of  the  Valley  floor  rise 
first  to  a  mass  of  rather  low  rufr<ied  foothills  varying  in  elevation,  as  they 
extend  westward,  from  800  to  loOO  feet.  Tliey  occupy  a  belt  about  fifteen 
miles  in  width  and  extend  from  the  southern  boundary  of  Shasta  County 
to  Suisun  Bay.  These  hills  have  been  carved  out  along  the  uJDturned 
edges  of  the  Cretaceous  formation.  The  rather  hard  Chico  sandstone 
which  marks  their  eastern  edge  has  given  rise  to  a  characteristic  topo- 
graphy of  innumerable  small  canyons  and  ridges,  with  a  general  east 
and  west  trend,  while  on  the  other  hand,  the  underlying  soft  Knoxville 
shales  which  mark  their  western  limits  have  given  rise  to  a  topography 
of  rather  broad  valleys  or  ])asins,  with  a  north  and  south  trend.  West 
of  these  foothills,  the  main  peaks  of  the  east  slope  of  the  Coast  Ranges 
rise  to  a  height  of  3000  to  -4000  feet  and  the  topography  of  the  country 
is  extremely  rugged,  having  been  carved  out  of  the  hard  resistant  rocks 
of  the  Franciscan.  In  Lake  County  the  rugged  topography  is  some- 
what broken  by  a  broad  level  valley  around  Clear  Lake,  which  drains 
into  the  Sacramento,  and  still  further  south  the  Napa  Valley  forms  a 
broad,  flat  plain,  draining  into  Carquinez  Straits. 

GEOLOGY. 

The  oldest  rocks  exposed  are  beds  of  altered  sandstone,  chert,  schist 
and  masses  of  intrusive  serpentine,  all  of  the  Franciscan  formation 
(Jurassic).  This  formation  extends  in  a  belt  from  southern  Shasta 
County  to  northern  Napa  County  and  varies  in  width  from  about  five 
miles  at  its  northern  end  to  25  miles  in  southern  Lake  County.  It 
covers  the  entire  western  portions  of  Tehama,  Glenn  and  Colusa  counties; 
about  nine-tenths  of  Lake  County ;  and  is  found  outcropping  in  the 
northeast  portion  of  Napa  County  and  along  the  east  side  of  the  Napa 
Valley.  Any  area  covered  by  this  formation  may  be  considered  as 
unfavorable  for  oil. 

Overlying  the  Franciscan  is  found  the  Cretaceous — the  only  forma- 
tion within  this  area  that  offers  any  promise  of  containing  oil.  The 
lowermost  Cretaceous,  known  as  the  Knoxville,^  consists  of  dark  thin- 
bedded,  fine-grained  carl)onaceous  shales.  "While  the  writer  has  no 
definite  data  on  the  proportion  of  carbonaceous  matter  in  the  shales, 

includes   the  Horsetown. 
4—13322 


50  CALIFORNIA   STATE  MINING  BUREAU. 

it  apparently  is  less  than  1  per  cent,  and  it  is  from  this  that  any  oil  found 
in  the  Knoxville  will  ueee-ssarily  come.  Interbedded  with  the  shales 
are  thin  beds  of  fine-grained  sandstone — generally  about  three  inches 
thick.     The  general  aspect  of  the  Knoxville  is  that  of  a  shale  formation. 

Above  the  Knoxville  is  found  the  uppermost  Cretaceous  or  Chico, 
which  consists  in  this  area  of  massive,  medium  coarse,  blue-gray  and 
greenish  sandstone,  which  turns  to  a  tawny  brown  on  weathering.  Inter- 
bedded with  the  sandstone  are  minor  beds  of  dark,  fine-grained  shale. 
The  contact  between  the  Knoxville  and  Chico  is  marked  generally  by  a 
thick  bed  of  conglomerate,  made  up  of  crystalline  pebbles.  In  Yolo 
and  Solano  counties,  the  uppermost  Chico  contains  several  beds  of 
dark  colored  more  or  less  carl)onaceous  shales,  averaging  in  thickness 
about  150  feet,  and  it  is  from  these  beds  that  any  oil  in  the  Chico  must 
come. 

The  main  body  of  Cretaceous  sediments  within  this  area  is  found 
occupying  the  foothill  belt  whicli  extends  from  southern  Shasta  County 
to  Suisun  Bay;  and  they  cover,  roughly,  an  area  of  about  15  miles  in 
width  across  the  centers  of  Tehama,  Glenn  and  Colusa  counties,  the  west 
half  of  Yolo  County  and  the  northeast  corner  of  Napa  and  the  northwest 
corner  of  Solano  counties.  The  maximum  thickness  is  nearly  30,000 
feet,  approximately  the  lower  22,000  being  Knoxville  and  the  upper  8000 
feet,  Chico.  The  general  structure  (with  some  exceptions  which  will  be 
noted  below)  is  that  of  a  great  monocline  dipping  at  an  angle  of  about 
35°  towards  the  Sacramento  Valley.  All  known  seepages  of  oil  in  the 
Sacramento  Valley  occur  in  this  belt  of  Cretaceous. 

Other  districts  in  which  the  Cretaceous  occurs  are  as  follows:  (a)  A 
small  area  of  Chico  occupying  a  synclinal  trough  just  south  of  the 
town  of  Lower  Lake,  Lake  County,  (b)  A  much-folded  ,,area  of 
Knoxville  shales  about  1500  feet  thick  in  tht  hills  along  the  west  side 
'!  of  the  Napa  Valley,  (c)  An  area  of  Knoxville  and  Chico  in  the  range 
of  hills  north  of  Vallejo  and  Benicia.  None  of  these  areas  show  any 
indication  of  oil. 

Tertiary  formations  occur  as  follows:  (a)  In  northern  Tehama 
County  in  the  foothills  along  the  valley  edge,  just  west  of  Redding,  are 
outcrops  of  nearly  flat-lying  beds  of  loose  sand,  conglomerate  and  vol- 
canic ash,  known  as  the  Tuscan  Tuff  formation,  of  Miocene  age.  The 
Tuff  is  lying  unconformably  upon  the  Chico  and  is  best  exposed  along 
the  south  fork  of  Cottonwood  Creek.  In  southern  Tehama  County  in 
the  hills  west  of  Corning,  beds  of  flat-lying  Tuscan  Tuff  are  found. 
(b)  In  northern  Glenn  County  in  the  foot  hills  along  the  valley's  edge, 
west  of  Orland,  is  a  series  of  buttes.  These  buttes  are  formed  of  beds 
of  Chico  sandstone  dipping  at  about  25°  to  the  east  and  capped  by  beds 
^  of  flat-lying  lava,  averaging  50  feet  in  thickness.     The  lavas  are  probably 

^^  of  late  Pliocene  age.      (c)   In  southern  Colusa  County  in  the  hills  west 

^^^  of  Williams  and  Arbuckle  and  occupying  the  lower  courses  of  Cortina 

*,  Creek,  Sand  Creek,  Elk  Creek  and  Petroleum  Creek,  are  beds  of  con- 

1  glomerate,  blue  sandstone  and  soft  blue  shales.     The  average  thickness 
^-        i  of  these  beds  is  about  1000  feet  and  the  age  is  probably  upper  Pliocene. 
They  are  lying  unconformably  upon  the  Chico. 

None  of  the  above  Tertiary  beds  show  any  evidence  of  oil. 

(d)  In  Yolo  County,  around  the  Capay  Valley,  there  is  a  Tertiary 
formation  about  800  feet  thick  consisting  mainly  of  beds  of  fine  clay, 


PETROLEUM   RESOURCES  OP   CALIFORNIA.  51 

intercalated  with  a.sh  beds  and  containing;,  near  the  top  and  bottom, 
beds  of  conglomerate  and  yellow  sand.  It  is  probable  tliat  tliis  forma- 
tion is  of  Eocene  age,  as  it  bears  a  marked  resemblance  to  the  lone 
(Tejon)  of  the  east  side  of  the  Sacramento  Valley.  It  is  found  in 
small  patches  along  the  floor  of  the  Capay  Valley,  and  in  tlie  hills  just 
north  of  the  town  of  Capay,  known  as  Duncan's  Bluffs,  it  forms  the 
nose  of  a  faulted  anticline.  Lying  unconforiuably  upon  the  Chico, 
along  the  valley's  edge,  it  probably  extends  as  far  north  as  Buckeye 
Creek  and  as  far  south  as  I'utaii  Creek.  It  lia.s  l)een  reported  tliat  the 
cla3-s,  when  boiled  with  ether,  show  a  light  amber  oil.  If  so,  this  oil  must 
liave  come  from  the  underlying  Chico,  as  the  lone  beds  contain  nothing 
that  would  form  oil.  (e)  In  the  vicinity  of  Vacaville,  Yolo  County, 
lliere  are  beds  of  diatomaceous  shales,  interbedded  with  muddy  blue 
shales  and  overlayed  with  conglomerate  beds.  Total  thickness  of  the 
formation  is  about  600  fe^t.  The  diatomaceous  shale  beds  average  about 
75  feet  in  thickness.  The  age  is  probably  middle  Eocene  (Meganos). 
This  Meganos  is  found  outcropping  along  the  flanks  of  an  anticline  which 
runs  along  the  Vaea  Valle}',  east  of  Vacaville.  It  ilso  outcrops  m  the 
range  of  hilLs  between  Vacaville  and  Winters^  where  it  di))s  eastward 
beneath  the  alluvium  of  the  Sacramento  Valley  at  an  angle  of  about 
30°.  (f )  In  the  small  range  of  hills  about  four  miles  southeast  of  Fair- 
lield,  known  as  tjie  Potrero  Hills,  there  are  beds  of  pink  diatomaceous 
shales  averaging  about  100  feet  in  thickness  and  interbedded  with  fine- 
grained white  sandstone.  The  total  thickness  of  this  formation,  as 
shown  by  the  Honolulu  Consolidated  "Well,  is  about  1100  feet.  The  age  is 
pro))ably  middle  Eocene  (Meganos).  Slight  showing  of  oil  has  been 
reported  in  the  shale,  (g)  Beginning  just  west  of  Fairfield  and  running 
south  to  Benieia  and  west  to  the  Napa  Valley  is  an  area  of  Pliocene  lava, 
which  lies  on  the  eroded  surface  of  the  Franciscan  and  Chico.  These 
lava  beds  continue  into  the  Napa  Valley  and  are  found  capping  the 
ridges  on  both  sides  and  at  the  head  of  the  valley,  (h)  A  small  amount 
of  Tejon  is  found  in  the  hills  just  southwest  of  Napa  City  and  in  the 
hills  just  east  of  Napa  Junction,  (i)  In  Lake  County,  south  of  the 
town  of  Lower  Lake,  there  is  about  5000  feet  of  Martinez  and  Tejon 
sediments,  overlying  the  Chico  in  a  synclinal  trough.  The  total  areal 
extent  is  about  five  square  miles,  (j)  In  southern  Lake  County  there 
are  numerous  lava  flows  overlying  the  Franciscan. 

INDICATIONS  OF   PETROLEUM. 

Indications  of  petroleum  on  the  west  side  of  the  Sacramento  Valley 
and  the  east  slope  of  the  Coast  Range  are  limited  to  the  Cretaceous  area 
in  Glenn,  Colusa,  Yolo  and  Napa  counties  and  possibly  the  Meganos 
area  in  the  Potrero  Hills.  A  reconnoissance  map  of  this  territory  is 
shown  on  Plate  V.  The  remainder  of  the  district  offers  no  inducement 
for  drilling,  and  no  further  discussion  of  it  will  be  given  here. 

Following  are  the  localities  in  the  above-mentioned  counties  in  which 
there  are  authentic  evidences  of  petroleum : 

In  Glenn  County,  there  are  no  actual  seepages  of  oil.  In  the  hills  west 
of  Orland,  however,  there  are  numerous  occurrences  of  gas  in  the  Chico 
sandstone.  In  Colusa  County,  seepages  of  light-amber  oil  of  a  paraf- 
fine  base,  with  a  gravity  of  20°  Baume  occur  in  the  Knoxville  shales  at 


52  CALIFORNIA    STATE    MINING    BUREAU. 

the  following  places:  (1)  Along  the  west  side  of  Bear  Valley,  near 
Wilbur  Spring,  there  is  a  line  of  seepages  beginning  in,  approximately 
See.  21,  T.  14  N.,  K.  5  W.,  and  continuing  .southward  to  See.  35,  T.  14  N., 
R.  5  W.  The  majority  of  these  seepages  occur  in  calcareous  springs  at 
the  contact  of  the  Knoxville  shales  with  the  nnderlying  Franciscan  chert 
and  serpentine.  The  maximum  yield  is  about  one  gallon  per  day.  In 
some  cases,  however,  the  seeps  are  actually  in  the  chert  and  serpentine. 
In  See.  35,  T.  14  N.,  R.  5  W.,  a  tunnel  has  been  driven  into  the  serpen- 
tine for  a  distance  of  about  fifty  feet,  with  the  result  that  as  much  as 
a  ])arrel  of  oil  has  been  found  in  certain  of  the  crevices  in  the  serpentine. 
The  occurrence  of  the  oil  in  the  serpentine  and  chert  may  be  accounted 
for  by  the  close  proximity  of  the  Knoxville  shales,  the  oil  apparently 
having  migrated  from  the  overlying  ccmipact  shales  into  the  fractures 
and  crevices  in  the  chert  and  serpentine  and  hence  may  be  regarded  a.s 
a  freak  occurrence  of  petroleum.  Any  tunnel  or  well  sunk  in  the  ser- 
pentine or  chert  with  the  expectation  of  encountering  a  pool  of  oil  is 
doomed  to  failure.  (2)  A  second  series  of  seepages  is  found  along  the 
axis  of  a  faulted  anticline,  running  north  and  south  through  Venado 
(Mountain  House).  These  occur  in  sandstone  beds  in  the  Knoxville, 
the  most  prominent  seep  being  found  in  the  SEI/4  of  Sec.  31,  T.  15  N., 
R.  4  W.  Wells  drilled  along  this  fault  at  various  times  still  continue 
to  show  small  amounts  of  gas.  (3)  A  third  series  is  found  along  the 
bottom  of  Sand  Creek,  in  Sec.  8,  T.  13  N.,  R.  3  W.,  where  the  creek  cuts 
across  the  axis  of  a  small  fold.     These  seeps  are  probably  in  the  Chico. 

In  Yolo  County,  along  the  axis  of  a  fault  in  the  Rumsey  Hills,  which 
mark  the  east  side  of  the  Capay  Valley,  there  are  numerous  salt  and 
sulphur  springs  from  which  it  is  claimed  green  oil  seeps.  The  springs 
are  in  the  middle  Chico.  At  the  time  of  the  writer's  visit,  most  of  these 
springs  had  ceased  to  flow,  so  the  report  could  not  be  verified.  In  the 
hills  just  south  of  Capay,  it  is  claimed  that  in  rainy  weather  there  are 
numerous  seepages  of  oil  and  gas  from  the  clay  of  the  lone  formation, 
and  a  sample  of  light  amber  oil  distilled  from  the  clay  was  shown  to  the 
writer  at  the  time  of  his  visit. 

In  the  Berryessa  Valley,  Napa  County,  there  are  several  notable  seep- 
ages in  the  Knoxville  shales.  They  are  located  as  follows:  in  the  SWy4 
of  Sec.  25,  T.  9  N.,  R.  3  W. ;  on  the  J.  W.  Harris  Ranch,  about  seven 
miles  north  of  ^Nfonticello ;  on  the  Zem  Zem  Ranch  in  the  SE^  of  See  34, 
T.  11  N.,  R.  4  AV.;  on  the  30()-foot  level  of  the  Knoxville  mine. 

In  Solano  County,  about  one  mile  southeast  of  C-annon,  in  Sees.  11 
and  14,  T.  5  N.,  R.  1  W.,  there  are  several  well  defined  'gas  blows.' 
These  gas  blows  occur  along  the  axis  of  a  fold,  in  the  Chico  sandstone, 
and  in  the  vicinity  of  the  'blow'  the  rocks  have  beeii  burirt  to  a  brick- 
red  slag. 

In  the  Potrero  Hills,  east  of  Fairfield,  there  are  numerous  seepages 
of  gas  reported  in  the  INFeganos  shales. 

STRUCTURE. 

IMate  V  shows  the  approximate  locations  of  the  major  folds  and  faults 
within  these  counties.  Fig.  4  shows  two  generalized  sections  across  this 
area.  The  majority  of  these  folds  (with  two  exceptions  which  are  noted 
below)  are  sharply  compressed  and  faulted  and  apparently  not  the 
most  favorable  type  of  .structure  for  the  accumulation  of  oil  in  appreci- 


PETROLEUM    RESOURCES   OF    CAIJPORNIA. 


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54  CALIFORNIA    STATE   MINING   BUREAU. 

able  quantities.  The  two  exceptions  consist  of  (1)  an  anticline  in  the 
Chico  sandstone  running  out  from  the  foothills  into  the  flat  of  the  Sacra- 
mento Valley  about  three  miles  southeast  of  Vacaville.  The  axis  of  this 
fold,  which  strikes  N.  45°  W..  mav  be  followed  from  Sec.  3,  T.  5  N.,  R.  1 
AV.,  to  Sec.  30,  T.  5  N.,  R.  1  E.  The  dips  of  the  flanlvs  vary  from  15°  to 
40°,  (2)  The  Potrero  Hills,  four  miles  east  of  Fairfield,  form  an 
elongated  dome  in  the  jNIeganos  formations.  The  axis  of  the  dome 
strikes  approximately  east  and  west  and  may  be  followed  from  Sec.  6  to 
Sec.  11,  T.  4  N.,  R.  1  W.  The  dips  on  the  flanks  vary  from  10=  to  20°  and 
the  plunge  at  the  east  and  west  ends  is  approximately  35°.  Both  of 
these  folds,  from  a  structural  standpoint,  are  favorable  for  the  accumula- 
tion of  oil. 

POSSIBILITIES. 

Factors  favorable  for  the  accumulation  and  production  of  oil  in  this 
area  are  as  follows:  (1)  The  presence  of  oil  as  shown  by  seepages.  (2) 
The  presence  of  structures  more  or  less  favorable  for  the  accumulation 
of  oil  in  small  quantities.  (3)  In  the  case  of  the  anticline  south  of 
Vacaville  and  the  dome*  in  the  Potrero  Hills,  the  structure  is  favorable 
for  the  accumulation  in  large  quantities. 

Factors  unfavorable  are  as  follows:  (1)  The  character  of  the  forma- 
tion present  (Cretaceous)  is  distinctly  unfavorable  for  the  formation 
of  petroleum  in  an  appreciable  amount.  (2)  Faulting  and  tilting  of 
the  strata  have  caused  a  considerable  percentage  of  whatever  oil  was 
originally  present  to  run  out  and  be  lost.  (3)  The  structure,  due  to 
sharp  folding  and  faulting,  is  not  favorable  for  the  accumulation  of  oil 
in  large  quantities,  except  in  the  two  cases  aliove  noted.  Summing  these 
factors  up,  it  would  appear  that  wells  drilled  along  the  axis  of  the  anti- 
clines and  faults  (shown  on  Plate  5)  should  obtain  showing  of  oil  and, 
possibly,  under  the  most  favorable  conditions,  obtain  small  quantities 
of  oil.  "Whether  these  small  quantities  of  oil  which  might  be  obtained 
would  be  of  commercial  value  can  only  be  determined  by  drilling.  Due 
to  the  favorable  structure  and  the  large  area  of  possible  accumulation, 
the  anticline  southeast  of  Vacaville  and  the  dome  in  the  Potrero  Hills 
may  be  considered  as  the  most  favorable  locality  to  test  out  this  district.^ 

Following  is  a  list  of  wells,  with  the  reported  results. 

Tehama  County.  Unnamed  well  in  Sec.  30,  T.  23  N.,  R.  4  W., 
drilled  to  a  depth  of  2020  in  the  Chico ;  showing  of  gas  reported. 

Colusa  County.  (1)  Unnamed  well  drilled  in  the  NW3/:4  of  Sec. 
23,  T.  20  N..  R.  5  W.,  about  the  year  1902 ;  depth  2900  feet :  located  in  a 
syncline  in  the  Chico;  show  of  gas  and  oil  reported.  (2)  Williams  Oil 
Company  'Brim  Well, '  located  in  the  SEi^-  of  Sec.  15,  T.  15  N.,  R.  4  W. ; 
drilled  to  a  depth  of  2540  in  the  Chico;  considerable  gas  reported. 
(3)  AYilliams  Oil  Company  'Granger  VTell.'  located  in  the  NEid  of  Sec. 
18,  T.  15  N.,  R.  4  W.,  on  the  axis  of  a  faulted  anticline;  drilled  to  a 
depth  of  600  feet  in  the  Knoxville  shales ;  good  showing  of  oil  reported 
from  75  to  600  feet.  (4)  "Williams  Oil  Company  well,  located  in  the 
NE>^  of  Sec  17,  T.  15  N.,  R.  4  W. ;  drUled  to  a  depth  of  1400  feet  in  the 
Chico:  sliowine  of  oil  and  gas  reported,  (o")  Williams  Oil  Company 
'Mountain  House  WeU/  located  in" the  SE34  of  Sec  18,  T.  5  N.,  R.  4  W"., 

'These  two  areas  are  now  being  tested  by  the  Honolulu  Consolidated  Oil  Co. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  55 

on  the  axis  of  a  faulted  anticline ;  drilled  to  a  depth  of  1300  feet  in  the 
Knoxville ;  good  showing  of  gas  reported  at  1042  feet ;  well  still  shows  a 
small  flow  of  gas.  These"  wells  of  the  "Williams  Oil  Company  were  drilled 
between  1901-1909.  (6)  At  the  present  time  (April,  1921)  the  Moun- 
tain  House  Standard  Oil  Company  is  drilling  a  well  in  the  NE^  of 
See.  18,  T.  15  N..  K.  4  AV.  A  depth  of  715  feet  has  been  reached  and  a 
good  showing  of  light  oil  is  reported.  (7)  Unnamed  well  in  NWi/4  of 
Sec.  32.  T.  15  N..  R.  4  AV. :  shallow-,  still  sliows  small  amount  of  gas. 

(8)  Three  wells  are  reported  as  having  been  drilled  on  Sand  Creek,  in 
Sees.  7  and  S,  T.  13  N..  K.  3  AV. ;  reported  depths  were  from  1000  to  1500 
feet  and  sliowings  of  gas  and  oil  were  said  to  have  been  encountered, 
one  well  still  showing  a  small  amount  of  gas.  These  welLs  are  located 
approximately   on  the  axis  of  an   anticline  in   the  uppermo.st   Chico. 

(9)  On  the  west  side  of  Bear  Creek,  about  one  mile  north  of  Wilbur 
Springs,  several  shallow  wells  were  driUed  near  the  contact  of  the 
Knoxville  and  Franeisean  and  close  to  the  seeps  that  occur  there. 
Showings  of  oil  and  gas  were  reported  from  these  wells.  (10)  In  the 
SWi/4  of  Sec.  35,  T.  15  N.,  R.  5  ^\.,  the  Herron  OilCompany  sank  a  well 
to  a  depth  of  1000  feet  in  the  serpentine.  At  the  present  time  a  tunnel 
is  being  driven  into  the  serpentine,  just  south  of  the  Ilerron  well,  by 
the  Blue  Ridge  Petroleum  Company.  Crevices  in  the  serpentine  have 
yielded  as  much  as  a  barrel  of  light  amber  oil.  As  stated  above  this 
can  be  regarded  only  as  a  freak  occurrence  of  petroleum.  The  oil 
undoubtedly  migrated  from  the  shales  which  are  found  outcropping  a  )out 
500  yards  east  of  the  tunnel.  (11)  At  the  present  time  the  Blue  Ridge 
Petroleum  Company  is  drilling  a  well  in  the  SWJ^  of  Sec  34,  T.  13  N., 
R.  3  W.  The  well  is  located  approximately  on  the  axis  of  a  sharply 
folded  anticline. 

Yolo  Count  v.  In  the  Capay  Valley,  about  two  miles  west  of  the  town 
of  Capay,  the  Lincoln-Esparto  Oilfields  Company  is  drilling  a  weU,  which 
is  apparently  located  on  the  top  of  a  dome  in  the  lone  formation.  Con- 
clusive proof  of  this  dome  structure  is,  however,  lacking. 

Solano  County.  In  the  NE^^  of  Sec.  24.  T.  5  N.,  R.  1  W.,  the 
Rochester  Oil  Company  drilled  a  well,  in  1901,  to  a  depth  of  1820  feet. 
Gas  was  encountered  at  1520  and  the  well  produced  at  the  rate  of 
20,000  cubic  feet  per  day  for  several  years.  In  19 J  9  the  production 
was  8,000  cubic  feet  per  day ;  since  then  the  production  has  steadily 
declined.  The  well  is  located  on  the  axis  of  a  well  defined  anticline  in 
the  Chico  sandstone.  In  the  SAVH  of  Sec.  13,  T.  5  N.,  R.  1  W.,  about  one- 
half  mile  northwest  of  the  Rochester  well  and  on  the  axis  of  the  same 
fold  the  Honolulu  Consolidated  is  now  drilling  a  well.  In  the  Potrero 
Hills,  about  four  miles  east  of  Fairtield,  the  Honolulu  Consolidated 
Company  is  drilling  a  second  well,  which  is  located  in  the  NE:^  of  Sec. 
9.  T.  4  "X..  K.  1  AV.  The  well  is  close  to  the  axis  of  a  dome  in  the 
Meganos  shale. 

In  addition  the  following  wells  were  drilled  in  the  Cretaceous  near 
Vallejo  without  obtaining  an  indication  of  petroleum:  Tlie  ]\lidas  Oil 
Company,  in  1914,  drilled  a  well  in  Sec.  20,  T.  3  N.,  R.  3  W,  to  a  reported 
depth  of  2000  feet.  AY.  Hauluth.  in  1916.  drilled  a  well  in  Sec.  4,  T.  3 
N.,  R.  3  W.,  to  a  reported  depth  of  1400  feet. 


56  CALIFORNIA    STATE    MINING   BUREAU. 

Napa  County.  In  the  Berryessa  Valley,  on  the  J.  AV.  Harris  Eauoh, 
about  seven  miles  north  of  ^lonticello,  the  Alount  Shasta  Oil  Company 
drilled  a  well  to  a  depth  of  400  feet  in  the  Knoxville  and  obtained 
showings  of  oil.  In  Sec.  25,  T.  9  N.,  R.  3  W.,  the  Fearless  Oil  Company 
drilled  a  Avell  to  a  depth  of  1475  feet  in  the  Knoxville.  obtaining  a 
showing  of  oil  at  270  feet.     These  wells  were  drilled  in  1904. 

(2)  DISTRICT  OF  THE  VALLEY  FLOOR. 

This  district  may  be  considered  as  embracing  the  flat-lying  territory 
of  the  valley  floor  proper. 

The  geological  formations  exposed  are  confined  to  small  ar(!as  in  the 
Hooker  Hills,  Tehama  Connty;  the  INIarysville  Buttes,  Sntter  Connty 
and  the  Montezuma  Hills  in  Solano  County.  These  three  gr  ninpi?  of  hills 
are  the  only  notable  interruptions  in  the  surface  continuity  of  the  flat- 
lying  lands  of  the  valley  floor.  The  remainder  of  the  district  is  covered 
by  recent  alluvium. 

The  Hooker  Hills  are  a  small  groui)  of  erosional  liills.  along  the 
Sacramento  River,  about. five  miles  north  of  Red  Bluff.  The  elevation 
is  about  500  feet.  A  study  of  the  topography  of  this  region  indicates  that 
these  hills  are  not  due  to  any  doming  up  of  the  strata,  but  rather  they 
are  to  be  regarded  as  an  erosioual  feature  of  the  topograpll3^  They  are 
a  part  of  an  old  flood  plain  of  the  Sacramento  River,  which  recent 
movements  have  elevated  and  the  present-day  streams  have  cut  down 
to  a  new  flood-plain,  leaving  the  hills  more  or  less  isolated.  Remains 
of  this  old  flood  plain  may  also  be  seen  in  the  well  defined  terraces  on 
both  sides  of  the  valley.  The  formations  exposed  are  the  Red  Bluff 
and  Tuscan  Tuff  formations.  The  Red  Bluff  formation  consists  of  about 
75  feet  of  coarse  red  conglomerate  of  Quaternary  age.  The  Tuscan  Tnff 
consists  of  about  500  feet  of  andesitic  tuft'  together  with  some  con- 
glomerate beds  and  lava  flows.  Some  of  the  tuft'  is  very  fine,  almost 
pumice  and  has  frequently  been  mistaken  for  diatomaceous  shale.  While 
there  is  no  direct  evidence,  the  Tuscan  formation  is  probably  underlayed 
by  the  Chico  sandstone.  The  so-called  gas  seepages  that  have  been 
reported,  are  nothing  more  than  iron  oxide  stain  in  the  conglomerate 
beds  of  the  Red  Bluft'  formation.  Neither  the  structural  conditions, 
nor  the  character  of  the  formations  are  favorable  for  the  accumulation 
of  petroleum  in  these  hills. 

The  Tuscan  Oil  Company  is  at  the  present  time  drilling  a  well  near 
Hooker  station,  in  Sec.  25,  T.  28  N.,  R.  4  E. 

The  ]\rarysville  Buttes  in  Sutter  County  are  the  most  notable  topo- 
graphical feature  of  the  Sacramento  Valley.  They  form  a  nearly  circu- 
lar group  of  mountains  with  a  diameter  of  about  ten  miles  and  rise 
from  an  elevation  of  about  100  feet  at  the  valley  floor  to  an  elevation 
of  2000  feet  in  the  central  peaks.  The  buttes  have  been  mapped  in 
detail  by  the  U.  S.  Geological  Survey.^  and  Dickerson-  has  recently 
described  the  sedimentary  rocks  that  are  found  there,  so  no  detailed 
description  of  the  geology'  is  given  herein. 

'Folio  17,  Marysville.     Folio  U.  S.  Geological  Survey. 

=Dickerson,  R.  E.  Eocene  of  the  Marysville  Buttcs-I^niversity  of  California.  Bulle- 
tin of  the  Department  of  Geology.     Vol.  7. 


PETROLEUM    RESOUKCES   OF    CALIFORNIA.  57 

The  buttes  consist  of  three  rings  of  different  formations ;  an  inner  core 
of  volcanic  rocks,  a  middle  v'mix  of  uptvn-ned  sedimentaries  consistino;  of 
the  Chieo  and  lone  formations  and  fin;dly  an  outer  ring  of  voleanic 
nuids  and  lavas.  The  sedimentaries  of  ("hico  and  lone  age  are  made 
up  mainly  of  tine  sandstones  and  clay  shales,  with  a  thickness  of  about 
1500  feet.  Showing  of  gas  has  been  reported  from  these  sediments 
from  time  to  time  and  in  1804  a  well  was  drilled  in  the  lone  formations 
about  one  mile  southeast  of  South  Butte.  A  depth  of  twenty  feet 
was  reached  and  a  small  How  of  gas  was  encountered,  which  can  still  be 
observed.  There  is  no  reason,  however,  to  believe  that  this  gas  is  con- 
nected with  petroleum  deposits  as  there  is  apparently  no  formation  in  this 
region  capable  of  forming  oil.  It  is  probable  that  the  tilting  up  of  the 
sedimentaries  against  the  central  core  of  volcanics  has  caused  the  marsh 
gas  (CH4),  which  is  present  in  varying  quantities  in  practically  all 
sedimentary  formations,  to  collect  in  a  noticcjiblo  degree  along  the 
upturned  edges  of  the  C'hico  and  lone. 

There  is  nothing  to  indicate  that  there  is  sufficient  gas  to  be  of  com- 
mercial value. 

The  ^Montezuma  Hills  cover  an  area  of  about  ten  s(piai'('  miles  in 
southern  Solano  County,  lying  along  the  Sacramento  River  at  a  point 
where  it  empties  into  Suisun  l^ay.  The  average  elevation  is  about  100 
feet.  The  formations  exposed  consist  mainly  of  soft  clay  shales,  with- 
out distinctive  strike  or  dip.  The  age  is  ])robably  late  Pliocene. 
Along  tlic  county  road  about  a  mile  south  of  Denverton  th(n-e  are  beds 
of  conglomerate  and  voleanic  ash,  striking  north  and  dipping  5°  to 
the  east.  Just  west  of  Rio  Vista  there  are  some  sandy  clay  beds, 
strikinn'  iiorth  and  dii)ping  about  30°  to  the  west.  From  these  meager 
dips  it  would  appear  that  the  hills  occupy  a  syncline  in  the  middle  of 
the  great  valley.  The  chief  interest,  however,  lies  in  the  fact  that  the 
diatomaceous  shale  (AFeganos)  which  outcrops  in  the  Potrero  Hills, 
probalil\'  continues  across  Hcnvcrton  slouuh  and  is  jjresent  l)enpath  the 
Montezuma  Hills.  These  shale  beds,  l)eiiig  diatonuu'eous,  may  for-in 
oil.  From  a  rough  survey,  the  hills  apparently  have  no  structure  that 
would  be  suitable  as  a  reservoir  for  any  oil  that  miglit  l)e  formed. 
However,  they  are  worthy  of  being  carefully  mapped  to  determine  if 
any  favorable  structure  is  present. 

The  greater  portion  of  the  valley  tloor,  which  is  covered  by  recent 
alluvium,  ott'ers  no  inducement  for  drilling.  At  the  same  time  this 
territory  can  not  be  cnndemned  outriglit.  While  it  may  contain  no 
positive  evidence  of  i)etruleum,  neither  does  it  contain  evidence  that 
oil  is  not  present.  The  recent  silt  and  alluvium  of  the  valley  tloor 
covers  all  evidence  that  might  tell  the  tale.  There  always  exists  the 
possibility  in  cases  like  this  tliat  the  fiat-lying  lands  may  be  underlayed 
by  i)r()ductive  folds.^ 

In  the  case  of  the  Sacramento  Valley,  however,  the  character  of  the 
formations  exposed  on  the  edges  makes  it  rather  doubtful  that  any  fold 
in  the  center  of  the  valley  would  be  pi'oductive. 

'This  matter  of  buried  anticlines  in  tlif  sreat  valley  is  discussed  in  detail  in  Chapter 
XIII,   Area  of  the   Sun   .loaquin  Valley. 


» 


58  CALIFORNIA    STATE    MINING   BUREAU. 

(3)   DISTRICT    OF   THE    EAST    SIDE    OF    THE   VALLEY    AND    THE 
FOOTHILLS  OF  THE  SIERRA  NEVADA. 

The  greater  part  of  this  distriet  has  been  mapped  more  or  less  in 
detail  by  the  United  States  Geological  Survey  and  the  detailed  geology 
can  be  found  in  the  following  folios :  Lassen  Peak,  15 ;  Marysville,  17 ; 
Smartsville,  18;  Sacramento,  5;  Placerville,  3;  Jackson,  11. 

The  oldest  roel«  exposed  are  known  as  the  Bedrock  series  and  con- 
sist of  ancient  schist,  gneisses  and  slates,  mainly  of  Carboniferous  and 
Jurassic  age,  together  with  associated  granitic  rocks.  These  formations 
constitute  the  core  of  the  Sierra  Nevada  and  probably  underly  the 
greater  part  of  the  area  under  consideration.  They  are  exposed  on 
the  surface  within  this  district  from  a  point  near  Oroville  as  far  south 
as  the  American  River.  Structurally  they  have  been  sharply  tilted 
and  folded. 

The  next  oldest  formation  consists  of  beds  of  medium-coarse  gray 
sandstone  and  sandy  shale  of  Chico  age  (Cretaceous).  The  surface 
exposures  of  Chico  are  not  extensive.  They  are  found  mainly  in  the 
deeper  canyons  of  eastern *Tehama  Count3%  and  northern  Butte  County, 
where  the  streams  coming  down  from  the  Sierra  Nevada  have  cut 
down  through  the  flat-lying  lavas  and  exposed  small  patches  of  the 
underlying  Cliico.  Roughly,  these  areas  of  the  Chico  formation  extend 
from  the  head  of  the  Sacramento  A'alley  as  far  south  as  Oroville.  A 
small  isolated  patch  has  been  recognized  on  the  American  River  near 
Folsom. 

The  Eocene  is  represented  by  the  lone  formation  (Tejon)  and  con- 
sists of  fine  clays  and  shales,  together  with  beds  of  impure  volcanic 
tuflf.  The  lone  is  found  as  far  north  as  AVheatland,  Yul)a  County, 
where  small  p^itclies  of  from  20  to  30  feet  are  exposed.  Near  Lincoln, 
in  Placer  County,  the  thickness  increases  to  100  to  200  feet  and  in 
Avestern  Sacramento  County,  south  of  the  American  River,  it  attains 
its  maximum  thickness  of  nearly  1000  feet.  In  this  district  it  lies 
upon  the  Bedrock  series  with  marked  unconformity  except  for  a  small 
area,  near  Folsom,  Avhere  it  is  found  unconformably  upon  the  Chico. 

The  other  Tertiary  formations  consist  of  beds  of  volcanic  ash,  known 
as  the  Tuscan  Tuff  (^Miocene)  which  is  overlayed  by  andesitie  and 
basaltic  lava  flows  of  Pliocene  age.  These  voleanies  cover  the  major 
portion  of  eastern  Tehama  and  northeastern  Butte  counties.  The  tulf 
is  found  unconformably  upon  the  Chico  and  has  a  maximum  thickness 
of  about  1000  feet.  The  lava  flows  are  found  more  or  less  conform- 
ably upon  the  tuff  and  vary  in  thickness  from  50  to  200  feet. 

The  general  structure  of  the  Cretaceous  and  Tertiary  formations 
within  this  district  is  that  of  a  great  monocline,  dipping  from  5''  to 
20°  to  the  west.  The  only  area  where  these  formations  have  been 
folded  is  found  at  Tuscan  Springs,  where,  in  a  crater-like  area  of  about 
80  acres  in  extent,  the  Chico,  Tuscan  Tuff  and  lavas  have  been  tilted 
up  into  a  nearly  circular  dome.  An  examination  showed  that  this 
structure  is  not  due  to  compressive  earth  movements,  but  rather  to  the 
efforts  of  a  batholitic  mass  of  lava  from  the  Lassen  Peak  range  of 
volcanoes  trying  to  force  its  way  up  through  the  overlying  formations. 


PETROLEUM    RESOURCES   OP   CALIFORNIA.  59 

111  the  vicinity  of  the  hot  mineral  springs  that  are  found  here,  shallow 
wells  have  encountered  small  amounts  of  gas.  It  is  probable  that  this 
gas  is  of  volcanic  origin  and  is  in  no  way  connected  with  petroleum 
deposits. 

There  is  no  possibility  of  finding  oil  in  the  lavas,  Tu.scan  Tuff,  or 
Bedrock  series.  Apparently  neither  the  Cliico  nor  tlie  lone  contain 
l)0(ls  that  would  form  oil,  or  structure  favorable  for  its  accumulation. 
AVliile  tlicre  have  been  occasional  reports  of  seepages  of  gas  and 
petroleum  from  this  district,  no  authentic  evidence  of  any  oil  or  petro- 
leum gas  has  been  found. 


60  CALIFORN'IA    PTATE    MINING    BUREAU. 


CHAPTER  VII. 
Area  of  the  Coast  Ranges  from  San  Francisco  Bay  as  Far  South 

AS  THE    PaJARO    RiVER. 

(Includes   the  counties  of  Contra  Costa.   Alameda,   San   Francisco,   San   Mateo, 

Santa  Clara  and  Santa   Cruz.) 

Q'ho  oil  possibilities  of  this  area  will  he  diseus.sed  by  counties. 

Contra   Costa  County. 

The  southwestern  one-third  of  the  county  has  been  mapped  in  detail 
by  Lawson.^  The  Dej>artnients«of  Geology  and  Paleontoloo^y  of  the 
University  of  California  have  carried  on  extensive  investigations  in 
the  northern  portions  of  the  county  and  in  the  territory  around  Mount 
Diablo.  Perhaps  no  other  i)art  of  the  Coast  Ranges  has  been  so  well 
studied.     Therefore  no  detailed  geolouy  will  be  given  here. 

The  strata  exposed  constitute  a  nearly  complete  section  of  the  Coast 
Range  formations  from  the  Franciscan  to  the  recent.  Structurally 
these  beds  have  been  sharply  tilted,  folded  and  faulted  into  a  large 
number  of  more  or  less  independent  geological  areas.  This  has  resulted 
in  preventing  any  one  fdrination  from  being  continuous  over  a  large 
area,  which  is  an  unfavorable  condition  for  the  accumulation  of 
petroleum. 

Those  formations  within  the  county  which  contain  beds  that  might 
form  oil,  consist  of  an  area  of  Chico  shales  on  the  north  side  of  -Blount 
Diablo:  a  small  area  of  middle  Eocene  organic  shales  (Meganos)  in 
the  vicinit.v  of  Blount  Diablo  and  finally  an  area  of  Monterey  diato- 
maceous  shale  in  the  San  Pablo  and  Rodeo  valleys  just  east  of  the 
Berkeley  Hills.  However,  none  of  these  organic^  shale  beds  are  con- 
tinuous over  a  sufficiently  large  area  to  form  any  great  amount  of  oil. 

Indications  of  petroleum  are  found  along  the  north  side  of  Mount 
Diablo,  about  seven  miles  due  south  of  Antio/h ;  and  in  the  S;ni  Pablo 
Valley,  east  of  the  Berkeley  Hills. 

The  ]\Iount  Diablo  indications  consist  of  small  intennittent  seeps  of 
light  green  oil,  found  in  the  vicinity  of  Oil  Canyon,  Long  Valley  and 
Deer  Valley.  Roughly,  the  territory  embraced  by  the  s(^epages  and 
wells  that  have  found  small  showings  consist  of  Sees.  13,  14,  15  and  23, 
T.  1  N..  R.  1  E.  The  formations  exposed  consist  of  beds  of  sand- 
stone and  shale  of  the  Chico,  dipping  in  a  monocline  of  about  65°  to 
the  north.  Beds  of  Eocene  age.  overlie  the  Chico  along  the  ridge  north 
of  Oil  Canyon.  Prospecting  for  oil  in  this  distriet  was  first  started 
in  1864,  when  several  wells  were  drilled  in  either  Sec.  13  or  14  to  a 
depth  of  about  300  feet  and  encountered  slight  showings  of  green  oil. 
In  1900  anotlier  attempt  was  made  and  several  more  wells  were  sunk 
to  shallow  dei)tlis  and  ()])tained  small  showings.  The  last  well  Avas 
drilled  by  the  Atlas  Development  Companv  in  1918  on  Oil  Creek,  in  the 
SE14  of*  Sec.  15,  T.  1  N.,  R.  1  E.  A  depth  of  1823  feet  was  reached 
and  as  no  showings  of  oil  were  encountered  the  well  was  abandoned. 


'U.  S.  Geological  Survey.     San  Francisco  folio  193.     By  A.  C.  Lawson. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  Gl 

About  15(H)  feet  up  tlic  cjiu^dii  and  due  cHst  aloiiir  the  strike  of  the 
formation  from  the  A  this  well,  is  an  old  hole  known  as  the  Harding 
welk  This  was  drilled  to  a  depth  of  978  feet  and  encountered  green 
oil  from  950  to  978  feet.  It  is  now  used  as  a  water  well  and  shows 
about  1  (piart  of  green  oil  per  day.  There  is  no  reason  to  believe 
that  future  drilling  in  this  region  would  show  any  better  results  than 
the  former  attempts. 

Indications  in  the  San  Pablo  Valley  consist  of  seepages  of  heavy 
black  asphaltic  oil  found  in  the  vicinity  of  Lauterwasser  Creek  and  in 
the  lower  end  of  the  valley  about  2  miles  east  of  the  town  of  San 
I'ablo.  A  detailed  geological  map  of  this  territory  can  be  found  in 
folio  19.T  and  Arnold  gives  a  brief  description  of  the  geology  and 
development   in   liulletin   'M)i.'- 

The  sti'ucture  in  the  vicinity  of  Lautci-wasser  Creek  consists  of  a 
I'ather  sharply  folded  anticline  pluniring  to  the  southeast  and  truncated 
at  the  northwest  end  by  a  fault.  The  oil  has  collected  in  tiie  sandy 
beds  of  the  Orinda  formation  (Pliocene),  having  been  formed  in  the 
underlying  diatomaccons  shale  beds  of  the  [Monterey  series,  which  at 
this  point  are  about  800  feet  thick. 

Beginning  in  1889  and  continuing  up  to  1900,  eight  wells  were 
drilled  on  this  structure,  the  depths  ranging  from  500  to  2700  feet, 
all  encountered  showings  of  oil  and  gas,  but  none  showed  suilfieient 
quantities  to  be  of  commercial  value.  At  the  lower  end  of  the  San 
Pablo  Valley  about  three  miles  east  of  the  town  of  San  Pablo,  five 
wells  were  drilled  to  1900  feet  along  a  syncline  in  the  Orinda  for- 
mation. Slight  showings  of  oil  were  encountered,  but  nothing  of 
commercial  value  was  devehsped.  The  oil  has  apparently  collected  in 
the  sands  of  the  Orinda  formations  from  the  ]\Ionterey  diatomaeeous 
shale,  which  outcrops  to  the  east  on  Sobrante  Ridge.  Neither  the 
geological  conditions  nor  the  results  of  wells  drilled  warrant  any 
further  attempts  at  development  in  this  area. 

Alameda   County. 

The  northwestern  portion  of  the  county''  and  the  area  around  Tesla 
and  Altamont*  have  been  mapped  by  the  United  States  Geological 
Survey. 

The  formations  exposed  within  the  county  consist  of  Franciscan, 
Cretaceous  and  a  nearly  complete  section  of  the  Tertiarv  sedimentaries, 
together  witli  numerous  lava  Hows  of  Pliocene  age.  The  Franciscan 
is  found  in  the  extreme  southeast  corner  of  the  county  and  in  a  long 
narrow  strip  along  the  west  side  of  the  Berkeley  and  San  Leandro 
hills.  It  also  is  probably  present  beneath  the  alluvium  of  the  flats 
that  border  the  east  side  of  San  Francisco  Bay.  The  Cretaceous,  con- 
sisting of  typical  Knoxville  shales  and  Chieo  sandstones,  is  found  over- 
lying the  Franciscan  in  a  rather  broad  area  near  the  top  of  the  western 
slope  of  the  Berkeley  and  San  Leandro  hills.  Other  areas  of  Creta- 
ceous arc  found  in  the  hills  south  of  Livei-more  and  in  the  vicinity  of 
Altamont  and  Tesla. 


'United  States  Geological  Survey  folio  193.     By  A.  C.  Law.son. 

=R.  Arnold.     Miner  Ranch  Oil  Field.      Bulletin   304.     U.  S.  Geological  Survey,   1907. 
Pages  339-3  42. 

^San  Francisco  folio  193.     By  A.  C.  Lawson. 
^Bulletin  603.      By  Anderson  and  Pack. 


62  CALIFORNIA    STATE    MINING   BUREAU. 

The  Tertiary  in  the  western  i)()i-tion  of  tlie  eonnty  eonsists  of  the 
Monterey  series,  together  with  ihe  Pliocene  seclimentaries  and  lava 
Hows.  In  the  eastern  portions  Ihci-c  are  outcrops  of  Eocene,  upper 
Miocene  and  Pliocene  beds.  The  .Monterey  series  in  the  Berkeley  and 
San  Ijeandro  hills  contains  diatonnu  eons  shale  but  not  in  sufficient 
quantities  to  form  any  notieeal)le  (juantities  of  petroleum. 

The  only  indication  of  oil  in  the  county  is  found  in  the  vicinity  of 
Tesla.  There  are  seepages  of  light-gravity  oil  in  sandy  beds  of  Miocene 
age.  The  seeps  are  best  exposed  on  the  Hamilton  Ranch  in  the  vieinity 
of  Sec.  15,  T.  3  S.,  R.  3  p].  It  is  very  probable  that  the  oil  was 
formed  in  the  underlying  Chieo  and  migrated  into  the  sandy  beds  of 
the  ]\Iiocene.  The  (Miieo  in  this  vicinity  is  known  as  the  Moreno  forma- 
tions and  consist  of  purplish  shah's  containing  organic,  nmterial.  It 
is  l)est  exposed  along  the  south  side  of  ("ori-al  Hollow,  between  Tesla 
ami  Carnegie.  Altogether  seven  wells  have  Iwcn  drilled  in  this  area, 
Hve  on  Sec.  15,  T.  3  S.,  R.  3  E.,  and  two  by  the  Standard  Oil  Com- 
pany, near  Altamont.  The  wells  on  See.  15  reported  small  showings 
of  light  oil,  those  at  AJtamont  obtained  no  indications.  In  191-1 
C.  A.  Waring^  wrote  a  brief  description  of  this  area  and  in  1915 
R.  Anderson  and  R.  Pack  made  a  detailed  survey-,-  giving  a  complete 
description  of  the  geology,  development  and  possibilities,  together  with 
an  areal  map.     Anderson  and  Pack's  conclusions  are  as  follows: 

"In  conclusion,  it  may  be  said  tiiat  the  probability  of  obtaining  a  large  quantity 
of  oil  in  tlie  Tesla  district  is  remote,  but  that  wells  producing  a  little  liglit-gravity 
oil  may  possibly  be  obtained  in  very  small  areas.  Such  wells  may  derive  their  oil 
either  from  sandy  beds  in  the  Cretaceous  or  from  the  lower  beds  of  the  unconformably 
overlying  Tertiary,  the  latter  offering  the  better  chances.  The  areas  whicli  offer  some 
Inducements  for  drilling  are  a  narrow  strip  along  the  soutli  flank  of  the  anticline 
which  trends  east  through  the  hills  north  of  Tesla,  where  the  dip  of  the  oeds 
steepens  abruptly,  and  an  area  of  low  dips  at  the  east  end  of  tliat  anticline,  where 
the  surface  is  formed  by  the  slightly  dijiping  undifferentiated  Miocene  and  San 
Pablo  formations.  Outside  of  these  two  areas  the  possibiUty  of  obtaining  oil  seems 
very  poor,  and  tlie  writers  believe  that  drilling  in  other  localities  will  prove  a  waste 
of  money." 

San   Francisco  County. 

The  county  of  San  Francisco  is  covered  entirely  by  beds  of  sand- 
stone and  chert,  together  with  intrusive  masses  of  serpentine  and 
basalt,  all  of  the  Franciscan  formation,  and  otfering  no  possibility  of 
producing  oil. 

San    Mateo   County. 

The  geology  of  the  county  has  been  described  and  mapped  i-n  detail 
by  Lawson''  and  Branner.* 

The  area  north  of  Halfmoon  Bay  may  be  considered  as  offering  no 
possibilities  for  oil,  the  formations  consist  for  the  most  part  of  the 
Franciscan,  together  with  a  granite  area  in  tlie  vicinity  of  ^lontara 
Mountain.  The  only  area  of  Tertiary  sedimentary  consists  of  a  narrow 
strip  of  Merced  (Pliocene),  running  southeast  from  a  point  on  the 
coast  near  the  San  Francisco  County  line  to  ^Milbrae  on  the  bay  side 
and  a  small  area  of  ^lartinez  (P^ocene)  in  the  San  Pablo  Valley. 

'Bulletin  G9.      California  State  Mining  Bureau,  i;il4.      Pages  439—1-10. 

-U.   S.  Geological   Survey.      Bulletin   603.        By  R.   Anderson   and  R.   W.   Pack    1915 
Pages  186-194. 

'U.  S.  Geological  Survey.     San  Francisco  folio  193.     By  A.  C.  Lawson. 

*U.  S.  Geological  Survey.     Santa  Cruz  folio  1G3.     By  J.  C.  Branner. 


PETROLEUM    RESOURCES   OF    CALIFORNIA,  63 

« 

In  the  area  smilli  oi'  HiiU'monn  l'><iy,  while  there  are  iiuuierous 
ovideiiees  of  petrolciiiii.  the  stnietural  conditions  are  not  favorable  for 
the  aceuranlation  in  l.ir^^e  amounts,  there  being  ;iii  absence  of  any 
closed  anticlines  in  the  I'urisinia  beds,  which  are  the  containers  of  the 
oil. 

The  oil  has  been  formed  in  the  ^Monterey  shale  beds  and  has  migrated 
to  the  overlying  i)or()Us  beds  of  the  Pnrisima  formation.  The  oil 
averages  abont  -18°  in  gravity  and  is  of  an  asphalt ie  base.  The  reason 
for  this  liglit  gravity  oil  of  an  asphaltic  base  in  beds  on  an  unsealed 
monocline,  may  be  exi>lained  by  the  fact  that  the  ])asal  l)eds  of  the 
Monterey  siiale  have  been  intruded  1)\-  basaltic  and  diabase  dikes. 
These  igneous  dikes  have  undoubtedly  ciaised  destructive  distillation 
of  the  oil,  with  the  result  that  a  heavy  residtiiuii  is  found  near  the 
intrusion  and  the  lightt'r  constituents  are  found  in  tin;  overlying 
Purisima  beds. 

'i'lie  pi-incipal  seepages  are  found  along  Purisima  Creek,  Tjol)itos 
Creek  and  Tunitas  ('re(^k  ami  are  in  beds  of  the  Purisima  formatioiu 
There  are  also  several  seeps  on  brandies  of  San  (fregorio  Creek.  On 
Purisima  Creek,  fourteen  wells  have  been  drilled  since  1880.  Seven 
of  these  are  reported  to  have  obtained  production  varying  from  ten 
to  thirty  barrels.  At  the  present  time  tliree  wells  are  pi'oducing,  yield- 
ing about  one  barrel  per  well  per  day  of  50°  oil.  These  are  known  as 
the  T.  B.  Wilkensen  wells.  Tlie  average  depth  is  about  700  feet  and 
they  have  been  drilled  entirely  in  tlie  Purisima  beds,  on  a  west  dipping 
monocline  of  about  30°. 

The  same  conditions  exist  on  Tunitas  Creek,  where  seven  wells  have 
been  drilled,  all  .reporting  small  showings.  A  distillation  of  the  oil 
shows  it  runs  70  per  cent  gasoline. 

The  possibilities  may  be  summed  uji  hy  saying  that  in  the  area  down 
the  dip  fi-om  the  seei)ages  mentioned  above,  small  wells  of  light  oil 
can  probably  be  obtained,  whether  these  would  be  sufficiently  large  to 
be  of  commercial  value  can  only  be  told  by  actual  drilling.  Any  devel- 
opment work  should  be  guided  hy  the  geological  conditions  as  shown  in 
U.  S.  G.  S.  folio  163. 

Santa  Clara   County. 

The  topograpliic  features  of  Santa  Clara  County  consist  of  the  Santa 
Clara  Valley  running  north  ami  smith  through  the  center  of  the  county, 
with  the  Santa  Cruz  ]\Iouiitains  bcn-dering  it  on  the  west  and  the 
Diablo  Kange  on  the  east. 

The  southwestern  portion  of  the  county  lias  l)een  majiped  by  the 
U.  S.  Geological  Survey.^ 

The  formations  of  the  Diablo  Range  within  this  area  consist  mainly 
of  Franciscan  beds.  On  the  western  edge  of  the  range,  east  of  San 
Jose  and  the  ^Mission  San  Jose,  there  are  outcrops  of  Cretaceous  and 
Tertiars'  which  may  underly  the  Santa  Clara  Valley  at  this  point.  The 
valley  proper  is  covered  with  recent  alluvium.  On  the  western  edf'e 
of  the  valley,  the  Santa  Clara  formation  (upper  Pliocene)  consistin<>- 
of  sands  and  gravels  and  clays,  is  found  outcropping.     BeneatJi   the 

'U.  S.  Geological  Suivey.     Santa  Ciuz  folio  163.     By  J.  C.  Branner. 


(54  .  CALIFORNIA    STATE    MINING    BUREAU. 

Saiitii  ("lara  and  forming  tin-  coiv  of  tlu'  Santa  Cni/  .Mountains  at  this 
point  are  Ix-cls  of  the  Franciscan  formation.  Along  the  western  edge 
of  the  county  whidi  is  pi-actically  paralkd  to  the  top  of  the  western 
slope  of  the"  Santa  Cruz  Range,  is  a  long  narrow  belt  of  Tertiary 
running  the  entire  length  of  the  county.  The  nortliern  portion  of  this 
belt  is  made  up  of  Oligocene,  Vaciueros  and  ^Monterey  beds.  South  of 
Loma  Prieta,  it  consists  mainly  of  Monterey  shale,  which  continues  as 
far  south  as  the  Pajaro  River,  wliere  it  turns  east,  crosses  the  range 
and  finally  dips  und(  r  the  Pliocene  beds  of  the  Santa  Clara  Valley  at 
Sargent. 

Oil  indications  witliin  the  (-(lunty  ai-c  limited  to  the  following  areas: 
(1)  Moody  (lulch.      (2)  Los(Jatos.      (;i)  Sargent. 

(1)  Moody  (;ulch  is  in  a  westerly  branch  of  i.os  Catos  Creek  about 
two  nules  south  of  Alma.  Tlie  gulch  may  be  entered  from  the  main 
county  road  from  Santa  Cruz  to  Los  Gatos.  Fig.  5  shows  the  general 
structure  of  the  region  and  the  formations  that  outcrop.  The  oil 
probably  formed  in  the  diatomaceeus  shales  of  the  Monterey  and  then 
by  reason  of  tlie  fault  .contact  has  migrated  into  the  porous  sands  of 
the  Vaqueros  and  San  Lorenzo  formation.  Drilling  was  first  started 
here  in  1880  and  all  together  about  85.000  barrels  of  oil  have  been 
shipped  from  the  Gulch.  The  wells  drilled  numlier  about  Ifi,  and  the 
average  depth  is  about  1200  feet.  The  gravity  of  the  oil  is  -45°  Baunie. 
The  reported  yield  from  the  old  wells  varies  from  ten  to  forty  barrels. 
Operations  cea.sed  about  1910,  but  recently  the  Trigonia  Oil  Co.  has 
taken  over  the  property  containing  the  old  Logan  and  Moody  wells 
and  is  starting  up  operations  again.  The  conditions  that  exist  in  the 
Gulch  probably  extend  for  a  mile  or  so  both  to  the  northwest  and 
southeast.  It  is  proljable  that  with  careful  management  the  area 
around  the  Gulch  could  l)e  nuuh^  to  produce  small  wells  of  commercial 
value. 

(2)  Los  Gatos.  Following  is  a  report  by  C.  A.  AA^aring^  of  this 
region : 

"The  Santa  Clara  Valley  region  east  of  Los  tJato.^;  is  covered  with  alluvial  gravel, 
sand  and  soil  so  that  the  underlying  formations  are  completely  concealed.  From  wells 
driiled  in  the  region  it  is  evident  lliat  this  land  is  underlain  Ijy  rocks  of  the  Monterey 
series   which   carry    some   oil. 

"Drilling  for  oil  has  been  carried  on  near  the  reservoir  of  the  San  Jose  Water 
Company,  on  the  San  Jose  road  two  miles  northeast  of  Los  Gatos.  Oil  indications 
were  first  noticed  on  the  ranch  of  Mr.  R.  C.  McPher.son  in  an  S.5-foot  well. 

"Four  wells  have  been  drilled  in  the  locality.  At  two  of  these  the  rigs  are  still 
standing  but  no  operations  are  at  present  being  carried  on.  In  a  1600-foot  well  back 
of  thv'  barn  on  the  property  of  Mrs.  H.  H.  Main,  gas  may  be  seen  bubbling  tlirough 
oil  which  fills  the  casing.  Some  oil  is  said  to  have  been  bailed  from  this  well  for 
use  as  fuel  by  the  owners.  A  well  on  the  soutli  side  of  San  Jose  road  is  said  to 
have  been  drilled  2530  feet  deep,  and  to  have  pierced  three  oil  strata." 

In  1918  the  Traders  Oil  Company  drilled  two  wells,  but  failed  to 
obtain  a  commercial  production.  AVell  No.  1  was  drilled  on  the 
:McGrath  Ranch  to  a  depth  of  200(1  feet  and  well  Xo.  2  was  located  on 
the  San  Jose  road  near  AValker  avenue  and  reached  a  depth  of  2675 

feet.  .^    , 

As   stated    above,    it    is   i)robable   that    the   region   is   underlaid    by 
'  Monterey  shale  containing  a  little  oil,  but  the  presence  of  Franciscan 
rock  on  both  sides  of  the  valley  restricts  the  shale  to  such  a  small  area 
that  production  on  a  commercial  scale  is  doubtful. 

'State  Mining  Bureau.     Bulletin  69,  1914,  page  470. 


PETROLEUM    RESOURCES   OF    CALIFORNIA. 


65 


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G6  CALIFORNIA    STATE    MINING   BUREAU. 

(3)  The  Sargeut  Ranch  fiekl  lies  approximately  in  T.  11  S.,  R.  3 
and  4  E.,  about  three  miles  west  of  the  railroad  station  of  Sargent. 
The  principal  development  has  taken  place  along  La  Brea  Creek.  The 
formations  outcropping  are  the  Franciscan,  ^Montere}'  sandstone  and 
shale  and  Pliocene  sands  and  clays.  The  oil  originated  in  the  diato- 
maeeous  shales  of  the  ^Monterey  and  has  collected  in  sandstone  beds  of 
the  same  formation.  The  Franciscan  is  found  outcropping  on  the 
hills  to  the  north  of  La  Brea  Creek  and  is  overlaid  by  the  Monterey 
formation  which  lies  in  the  form  of  a  crescent  dipping  at  about  45° 
to  the  southeast.  Westward  the  Monterey  continues  as  far  as  a  mile 
west  of  the  Santa  Clara-Santa  Cruz  County  boundary,  where  it  is 
truncated  by  the  San  Andreas  fault.  In  its  soutliward  extension  it  is 
terminated  by  a  fault  along  the  Pajaro  River.  On  the  lower  portion 
of  La  Brea  Creek  and  in  the  hills  just  west  of  Sargent,  the  ^Monterey 
dips  under  the  sandstones  and  shales  of  the  Purisima.  These  later 
beds  are  dipping  at  an  angle  of  45°  to  the  south.  In  the  Lomas 
]\Iuertas,  soutli  and  east  of  Sargent,  there  are  beds  of  sand  and  clay 
probably  of  upper  Pliocene  age.  The  axis  of  a  small  anticline  runs 
southeast  up  the  canyon -just  east  of  Sargent  Station  and  finally  flattens 
out  into  an  east  dip  which  is  the  general  inclination  of  the  strata  in 
the  Lomas  Muertas.  There  have  been  about  twenty  wells  drilled  along 
La  Brea  Creek,  all  ol)tained  a  showing  of  oil.  Those  which  have  pro- 
duced on  a  commercial  scale  are  located  about  two  miles  up  the  creek 
from  the  state  highway.  The  average  depth  is  about  1500  feet  aud  the 
oil  is  obtained  from  sandstone  beds  on  a  monocline  in  the  ]\Ionterey. 
The  gravity  averages  about  18°  Baume. 

At  the  present  time  the  AVatsonville  Oil  Company  is  operating  nine 
wells  with  a  total  production  of  75  barrels  per  day,  which  is  apparently 
the  maximum  yield  of  the  field.  On  Pescadero  Creek  and  near  Chit- 
tenden, a  number  of  shallow  wells  were  drilled  obtaining  small  show- 
ings of  heavy  oil.  Due  to  the  fault  contacts  on  the  west  and  south  and 
the  serpentine  contact  on  the  north,  there  is  no  hope  of  extending  the 
field  in  those  directions.  On  the  ea.st  the  oil-bearing  sand  of  the  Mon- 
terey dips  so  steeply  nnder  the  Pliocene  beds,  that  the  chance  that 
they  would  be  within  reach  of  the  drill  is  doubtful.  On  the  axis  of 
the  anticline  just  east  of  Sargent  in  the  Lomas  ^luertas  (San  Benito 
County)  there  is  a  possibility  that  these  beds  may  be  reached  by  drill- 
ing. The  Shell  Company  is  at  tlie  present  time  drilling  a  prospect 
well  here. 

Santa  Cruz  County. 

The  area  lying  north  and  west  of  the  town  of  Santa  Cruz  has  been 
mapped  in  cletail  by  the  U.  S.  Geological  Survey,^  and  it  is  in  this 
portion  of  the  county  that  the  principal  indications  of  petroleum  occur. 
Briefly,  the  geology  is  as  follows: 

In  the  area  around  Ben  Lomond  ^fountain,  running  from  Little 
Basin  to  the  town  of  Santa  Cruz,  the  formations  consist  of  granitic 
rocks,  together  with  areas  of  ancient  crystalline  schists.  In  the  region 
to  the  north  of  this  crystalline  area  there  are  outcrops  of  the  San 

'U.  S.  Geological  Survey.     Santa  Cruz  folio  163.     Bv  J.  C.  Branner. 


PETROLEUM    RESOURCES   OF    CAIJFORNIA.  67 

Lorenzo  ft)niiatioiis,  tlio  \'a<iueros  sandstone  and  the  diatomaeeous  shale 
of  the  ]\Ionterey.  These  have  been  all  sliai[)ly  folded  and  faulted. 
The  Monterey  contains  numerons  seepages,  lint  tliere  is  an  almost  total 
lack  of  an  overlyintr  formation  wliieh  eonld  aet  as  a  reservoir.  This, 
together  with  the  ntifavoi'ahh'  structural  conditions,  make  the  possi- 
bility of  obtaining  oil  in  paying  quantities  in  this  area  remote.  In 
some  cases,  by  reason  of  faulting,  the  oil  has  migrated  from  the  Mon- 
terey into  the  underlying  beds  of  the  Vaqueros  and  San  Lorenzo.  It 
is  probable  that  wells  drilled  in  this  area  in  either  the  ^Monterey,  or 
the  underlying  Tertiary  beds  will  encounter  small  showings  of  oil,  but 
not  of  sufficient  size  to  be  of  commercial  importance. 

In  the  area  between  Ben  Lomond  ^Mountain  and  the  coast,  the 
Vaciueros  and  ^lonterey  lies  in  a  monocline,  dipi)ing  al)uut  25°  to  the 
southwest.  The  [Monterey  is  heavily  lutuminized  and  has  been  exten- 
sively quarried  for  asphaltum.  This  feature  has  been  covered  in  a 
report  by  Eldridge.^ 

The  lack  of  reservoir  formations  above  the  Monterey  and  the  general 
monoclinal  structure  are  not  favcrable  conditions  for  the  accumula- 
tions of  any  commercial  quantities  of  oil  in  this  area. 

The  remainder  of  the  county  which  embraces  the  district  lying 
between  Santa  Cruz  and  Watsonville  and  southwest  of  the  Santa  Cruz 
[Mountains,  may  be  likened  to  a  coastal  plain.  In  the  country"  north 
of  Ai)tos  this  likeness  is  not  generally  api)arent,  as  the  hills  frequently 
rise  to  a  height  of  1500  to  1800  feet.  Between  Aptos  and  Watsonville, 
however,  the  county  is  characterized  by  low  rolling  hills,  varying  in 
elevation  from  100  to  500  feet.  The  northea=;t  boundary  is  marked  by 
the  steep  escarpment  of  the  west  side  of  the  Santa  Cruz  [Mountains, 
formed  by  the  San  Andreas  fault.  The  greater  portion  of  the  district 
is  covered  by  loo.se  incoherent  sands  and  clay,  varying  in  color  from 
yellow  to  brown  and  having  no  distinctive  strike  or  dip.  The  age  is 
not  definitely  known,  but  very  probably  they  belong  to  the  Merced 
formation  (upper  Pliocene).  "With  the  exception  of  an  area  about 
three  miles  northeast  of  Watsonville  (which  will  be  discussed  below) 
no  distinctive  structure  could  be  made  out  in  these  beds.  Near  the 
town  of  Santa  Cruz,  the  [Monterey  shale  apparently  dips  under  the 
[Merced  beds  and  very  probably  it  underlies  this  entire  area.  Between 
the  San  Andreas  fault  and  the  Santa  Clara  County  line,  is  an  area 
of  [Monterey  shale,  referred  to  in  the  article  on  Santa  Clara  County. 
The  shale  apparently  lies  in  a  synclinal  trough ;  the  eastern  limb  rest- 
ing on  the  Franciscan;  the  axis  of  the  syneline  approximately  coincid- 
ing with  the  county  line  and  the  west  limb  is  faulted  against  the  Merced 
beds  by  the  San  Andreas  fault. 

On  the  [Mount  [Madonna  road,  about  four  miles  north  of  Watsonville 
and  about  one-half  mile  south  of  the  Casserly  school,  is  the  axis  of  a 
small  anticline  in  the  [Merced  beds,  the  west  limb  of  which  is  sharply 
compressed  against  the  [Monterey  shales  by  the  San  Andreas  fault.     It 

'Twenty-second  annual  report  of  the  U.  S.  Geological  Survey. — The  Asphalt  and 
Bituminous  Rock  Deposits  of  the  United  States.  By  G.  H.  Eldridge.  1901.  Pages 
381-407. 


68  CALIFORNIA   STATE    MINING   BITREAU. 

is  ill  tills  area  that  the  iiidieations  of  oil  oceiir.  On  the  Webb  Ranch, 
it  is  reported  that  two  shaUow  wells  were  drilled  and  obtained  gas.  In 
the  canyon  just  back  of  the  ranch  house  there  is  apparently  a  dn- 
seepage  of  black  oil.  On  the  Hughes  Ranch,  one  well  was  drilled  up 
the  canyon  just  back  of  the  house.  A  deptli  of  7(X)  feet  was  reached 
and  considerable  gas  was  encountered.  At  the  present  time  the  Cymric 
Oil  Company  is  drilling  a  well  at  this  location.  This  area  may  be 
considered  as  worthy  of  being  tested.  As  regards  the  remainder  of  the 
area  under  discussion  it  is  worthy  of  being  thoroughly  investigated  for 
structure  before  being  condemned.  It  is  apparently  underlaid  by 
bituminous  shales  of  the  Monterey  and  should  detailed  mapping  reveal 
any  favorable  structure  in  the  Pierced  beds,  the  locality  would  be  worth 
testing. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  69 


CHAPTKR  VIII. 

Coast  Ranges  from  the  Pajaro  River  as  Far  South  as  the  Santa 

Maria  River. 

(Includes  the  counties  of  San  Benito.  Monterey  and  San  Luis  Obispo.) 

San    Benito   County. 

San  H.^nito  Tountv  oe.-npios  n  nearly  ivrtaii-ulai-  area  in  t lie  heart 
of  the  :\Iid(ne  Coast"  Haiiues.  Tlie  hnigth  rnnniuK  nortli  and  south  is 
about  66  miles  and  the  width  east  and  west  is  approximately  24  miles. 
The  western  portion  is  occupied  by  the  (Javdan  Range.  The  San 
Benito  and  Tres  Finos  Valleys  run  throngli  tlie  center  of  the  county 
for  almost  its  entire  length.  The  eastern  portion  is  occupied  by  the 
Diablo  Range.  With  the  exception  of  the  tlat  plain-like  area  north  of 
Hollister  and  the  narrow  valleys  of  the  Tres  Finos  and  San  Benito 
Rivers,  the  county  may  be  regarded  as  mountainous.  In  the  Diablo 
Range  the  Vallecitos  forms  a  rather  high  structural  valley  near  the 
southeastern  portion  of  the  county.  The  Fanoche  River  cuts  through 
the  range  about  the  middle  of  the  eastern  boundary,  draining  into  the 
San  Joaquin  and  forming  the  Fanoche  Valley. 

Tlie  general  geology  of  the  county  is  as  follows:  Tlie  (Javilan  Range 
is  composed  of  ancient  crystalline  schist  and  limestone,  together  with 
associated  granitic  rocks,  all  known  as  the  Santa  Lucia  Series 
(Falcozoic).  The  northern  portion  of  the  Diablo  Range  within  the 
county,  embracing  roughly  the  area  east  of  Tres  Finos  Creek  and  north 
of  the  Fanoche  Valley  is  composed  of  rocks  of  the  P'ranciscan  forma- 
tion. The  Franciscan  is  also  present  in  the  extreme  southeastern  por- 
tions of  the  eounty,  in  the  vicinity  of  the  New  Tdria  mine.  By  the 
nature  of  the  formations  these  areas  may  be  considered  as  impossible 
for  oil. 

The  sedimentary  rocks  are  found  as  follows:  (1)  In  the  area  between 
Hollister  and  the  Lomas  Muertas.  (2)  In  the  Tres  Finos,  San  Benito 
and  Santa  Ana  Valleys.  (8)  In  the  Diablo  Range  south  of  Fanoche 
Valley,  and  finally  in  the  extreme  southwestern  portion  of  the  county. 

1.     Area  between  Ilollist,  r  and  the  Loinas  Muertas. 

In  the  area  north  of  Hollister  the  exposures  consist  of  sands  and 
gravels  probably  of  Fliocene  age.  In  the  Lomas  Muertas,  which  are  a 
low  range  of  hills,  just  east  of  Sargent  station,  the  beds  exposed  con- 
sist of  fine  clays  and  sandy  shales,  also  probably  of  Flioeene  age.  As 
stated  in  the  article  on  the  Sargent  Field  (Chapter  VII),  the  bitumi- 
nous shales  and  sands  of  the  IMonterey,  dip  under  these  Pliocene  beds 
and  are  probalily  present  in  the  Lomas  ]\Iuertas.  AVhether  they  would 
be  within  the  reach  of  the  drill  in  tlie  area  under  consideration  is 
doubtful.  The  axis  of  a  small  anticline  runs  southeast  up  the  canyon 
just  east  of  Sargent  station.  The  Shell  Company  of  California  is  at 
the  present  time  drilling  a  prospect  well  here  and  the  results  obtained 
in  this  well  should  either  prove  or  disprove  the  district. 


70  CALIFORNIA   STATE    MINING   BUREAU. 

2.  Area  of  the  Upper  San  Benito,  Tres  Pinos  and  Santa  Ana  Valleys. 
In  the  area  between  ITollister  and  San  Benito,  including  the  San 

Benito,  Tres  Pinos  and  Santa  Ana  Valleys,  the  formations  exposed 
consist  of  sandstone  and  shales  of  the  Chico ;  massive  brown  sandstones 
of  the  Vaqneros  formation ;  light  grey  sandstones  and  clays  of  the 
Santa  ^Margarita ;  sands,  gravels  and  clays  of  the  upper  Pliocene. 
These  formations  have  been  sharply  folded,  faulted  and  compressed 
into  an  area  between  the  Gavilan  and  Diablo  Kanges  of  ten  miles  in 
Avidth  and  about  30  miles  in  length.  Section  AB,  Fig.  6,  shows  the 
general  structure  and  relationship  of  the  formations  in  the  vicinity 
of  Tres  Pinos.  This  area  may  be  eon.sidered  as  unfavorable  for  oil  for 
the  following  reasons:  (1)  No  evidence  that  any  of  the  formations  con- 
tain organic  shale  beds.  (2)  No  evidences  of  petroleum  such  as  seep- 
ages, although  the  formations  have  been  faulted  so  that  if  the  bed 
contained  oil,  it  Mould  be  free  to  run  out.  (3)  The  narrow  area  occu- 
pied by  the  sedimentaries  is  too  small  to  allow  any  appreciable  collec- 
tion of  oil  even  if  the  beds  did  contain  it'.  There  has  been  no  drilling 
in  this  region. 

3.  Diablo  liangc  South  of  Panoche  Tallcij. 

The  Diablo  Range  from  the  Panoche  Valley  south  has  been  thor- 
oughly mapped  in  detail  by  the  U.  S.  Geological  Survey,  so  no  detailed 
geology  will  be  given  herein. 

The  only  localities  in  this  area  that  show  the  slightest  indication  of 
oil  are  the  Vallecitos  and  Ciervo  Districts.  The  following  is  a  por- 
tion of  Anderson  and  Pack's^  report  on  these  two  districts.  Section 
CD,  Fig.  6  (adapted  from  the  report),  shows  the  general  structure  and 
elationship  of  the  formations  in  the  two  districts : 


1 


"Vallecitos   District.     General    Features. 


"The  VaUecitos  offer.s  an  excellent  example  of  a  completely  inclosed  synclinal  basin. 
The  topography  roughly  reflects  the  structure,  so  that  it  is  at  once  a  structural  and 
topographic  basin.  The  valley  Is  a  little  over  10  miles  long  from  east-southeast  to 
west-northwest  (not  including  the  valley  of  Pimental  Creek  on  the  west,  which  is 
really  a  continuation  of  it)  and  has  an  average  width  of  about  2  miles  b<^tween  the 
bases  of  the  steeper  hill  slopes  bounding  it.  It  is  divided  into  an  eastern  and  a 
western  part  by  a  low  drainage  divide  and  is  drained  by  two  intermittent  streams 
that  have  cut  deep  canyons  northwai-d  across  the  structure  at  eitlier  end  of  the  valley. 
The  two  divisiors  of  the  ba?in  account  for  the  name,  which  means  'the  little  valleys.' 
The  structural  trough  is  produced  by  the  Cretaceous  and  Tertiary  formations  dipping 
rather  steeply  southward  on  the  north  side  and  even  more  steeply  nortliward  on  the 
south  side,  the  axis  of  the  trough  corresponding  approximately  to  the  bottom  of  the 
valley.  On  the  east  the  trough  is  closed  where  the  beds  circle  around  the  end  of 
the  valley  east  of  San  Carlos  Creek  and  dip  at  a  moderate  angle  westward.  Toward 
the  west  end  the  sides  of  the  trough  gradually  steepen,  but  the  syncline  continues  up 
the  valley  of  Pimental  Creek. 

"The  formations  involved  in  this  syncline  are  as  follows:  (a)  The  Panoche  forma- 
tion, mildly  concretionary  sandstone,  which  forms  the  main  mass  of  the  Griswold 
Hills,  on  the  north,  and  appears  on  the  main  ridge  of  the  Diablo  Range,  to  the  south; 
(b)  The  Moreno  formation,  which  on  the  north  occurs  along  a  belt  of  extremely 
variable  width  and  in  places  hardly  traceable  and  which  owing  to  faulting  is  not 
recognizable  with  certainty  in  the  western  portion  of  the  southern  flank;  (c)  The 
Martinez  (?■)  formation,  of  mingled  concretionary  sandstone  and  clay  shale,  wliich  is 
so  mucli  like  some  of  the  other  formations  that  its  identification  and  delimitation 
are  in  many  places  difficult;  (d)  The  Te.jon  formation,  mostly  of  white  sandstone 
and  only  locally  traceable;  (e)  The  Kreyenhagen  shale,  soft  white  diatomaceous  shale, 
and  hard  siliceous  .«liale  or^curring  pretty  continuously  on  both  flanks;  (f)  The 
Vaqucros  (lower  Miocene),  which  encircles  the  valley  and  forms  the  steep  sandstone 
hiPs  bordering  the  lower  slopes;  and  (g)  the  .Tacalitos  and  Etchegoin  formations 
composed  largely  of  black,  red  and  green  clays  with  interbcdded  sand  and  gravels, 
representing  the  later  Miocene  and  occupying  the  core  of  the  s.yncline.  Descriptions 
of   the  thickness,    distribution   and   composition   of  these   formations   will   be   found   in 


'U.  S.  Geological  Survey.     Bulletin  603.     Anderson  and  Pack,  1915. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  71 

the  separate  sections  of  this  report  devoted  to  them.  Of  these  formations  those  of 
chief  importance  with  relation  to  oil  are,  as  in  the  Coalinga  district,  the  diatomaceous 
shales  of  the  Moreno  and  the  Kreyenliagen  and  the  sandy  beds  overlying  them. 
Seeps  occur  in  the  Moreno  north  of  the  west  end  of  the  Vallecitos  and  in  supposedly 
equivalent  beds  in  Mantillas  Canyon  south  of  the  valley.  (See  p.  123).  Seeps  and 
indications  of  oil  occur  in  the  Kreyenhagen  shale  at  numerous  places  along  the  south 
flank  of  the  syncline  and  also  at  its  east  end.  In  addition  surface  indications  of  oil 
occur  locally  in  the  Vaqueros  and  at  one  place  in  the  clays  of  the  Jacalitos  and 
Eti-hegoin  formations.  It  is  therefore  evident  that  petroleum  is  present  and  pretty 
well  distributed  along  the  flanks  of  this  fold,  and  the  main  ((uestion  to  decide  is  as 
to  the  amount  that  may  be  recoverable.  In  order  to  discuss  the  conditions  and  the 
evidence  bearing  on  this  point  somewhat  more  in  detail,  the  district  will  be  divided 
into  two  parts — the  steeply  tilted  south  Hank  of  the  fold  and  the  similarly  steep  north 
flank  which  merges  with  the  more  gently  tilttd  east  end  of  the  syncline,  For  a  more 
detailed  discussion  of  the  surface  evidences  of  oil  the  reader  is  referred  to  the  previous 
section  of  this  report  dealing  with  the  seeps  and  other  indications  offered  by  the 
various  formations,      (pp.  123-136). 

"South   Flank  of  the  Vallecitos  Syncline. 

"Along  the  south  side  of  the  Vallecitos  the  mountains  and  descending  ridges  are 
formed  by  a  continuous  monocline  dipping  steeply  toward  the  valley.  This  monocline 
is  the  southern  flank  of  the  Vallecitos  syncline.  From  San  Carlos  Creek,  at  the  east 
end  of  the  Vallecitos,  it  strikes  westward  for  about  5  miles  and  then  bends  at  an 
angle  of  about  35°  and  strikes  nortliwestward  to  the  west  end  of  the  valley.  Beyond 
that  place  the  same  steep  monocline  continues  in  a  similar  direction  along  the  south 
side  of  the  valley  of  Pimental  Creek.  The  area  of  chief  interest  in  the  present  con- 
nection is  the  belt  of  Tertiary  strata  at  the  outer  edge  of  the  foothills.  These  beds 
consist  of  the  Kreyenhagen  shale  and  the  sandstone  and  shale  of  the  Vaqueros 
formation  at  the  edge  of  the  hills,  overlain  by  the  thick  variegated  clay  of  the 
Jacalitos  and  Ktchegoin  formations. 

"Tlie  dip  of  the  Vaqueros  and  older  beds  varies  from  about  40°  to  the  vertical. 
For  much  of  the  way  the  formations  are  overturned  along  the  front  of  the  hills  and 
appear  to  dip  southward.  The  overturning,  however,  is  not  believed  to  extend  very 
far  below  the  surface.  The  overlying  Jacalitos  and  Ktchegoin  formations  are  likewise 
steep  along  their  contact  with  the  Vaqueros,  standing  vertically  in  places  and  nowhere 
dipping  less  than  30°.  The  clip  decreases,  however,  northward  toward  the  axis  of 
the  Vallecitos  syncline. 

"The  Kreyenhagen  shale  and  the  Vaqueros  are  oily  practically  throughout  their 
extent  along  the  south  side  of  the  Vallecitos,  the  siliceous  diatomaceous  shale  of  the 
Kreyenhagen  and  similar  material  interbedded  with  the  Vaqueros  being  impregnated 
with  oil,  so  that  at  almost  any  point  when  broken  they  give  off  an  odor  of  petroleum. 
The  sandy  strata  of  the  Vaqueros  likewise  are  locally  impregnated  where  in  contact 
with  the  shales.  At  a  numljer  of  i)laces  where  the  beds  are  traversed  by  gullies, 
the  oil  oozes  out  of  tliem.  and  several  wells  have  been  drilled  near  by  on  the  strength 
of  these  apparently  promising  indications.  Among  such  seeps  and  wells  the  following 
may  be  mentioned:  In  the  canyon  of  the  Hamiltonian  well,  1^  miles  south  of  John 
Ashurst's  place,  north  of  the  center  of  Sec.  24,  T.  17  S.,  R.  11  E.,  oil  rises  to  the 
surface  out  of  the  overturned  and  broken  strata  near  the  contact  between  the  sand- 
stone of  the  Martinez  (?)  formation  and  the  white  sandstone  of  the  Tejon.  It  doubt- 
less has  its  source  in  the  Kreyenhagen  shale,  which  owing  to  the  local  overturn, 
here  underlies  the  relatively  thin  Tejon  formation.  The  Hamiltonian  well. was  drilled 
without  success  about  1500  feet  down  into  the  stratigraphically  underlying  but  owing 
to  the  overturn  apparently  overlying  sandstone  beds  of  the  Martinez  (?).  Another 
seep  occurs  in  the  Kreyenhagen  shale  in  the  creek  bed  in  the  SEJ  Sec.  16  of  the 
same  township.  No  wells  have  been  drilled  here.  A  third  locality  is  in  the  canyon 
of  the  San  Carlos  well  near  the  center  of  Sec.  8.  There  and  in  the  next  small  canyon 
to  the  northwest  oil  seeps  out  of  the  same  belt  of  shale  and  also  appears  abundantly, 
impregnating  the  sandstone  and  shale  of  the  Vaqueros  formation  throughout  their 
thickness.  Still  another  seep  appears  at  the  summit  of  the  Kreyenhagen  shale  in  a 
canyon  at  the  west  side  of  the  SEJ    Sec.   6. 

"The  San  Carlos  well  was  drilled  by  hand  to  a  depth  of  approximately  170  feet 
in  the  oily  Kreyenhagen  shale  about  20  years  ago  and  gave  the  region  some  notoriety. 
When  bailed  dry  the  well  will  fill  with  oil  in  the  course  of  a  few  hours.  In  this  way 
it  was  estimated  originally  that  it  might  produce  from  1  to  5  barrels  of  oil  a  day, 
but  its  capacity  has  never  been  tested  and  it  is  very  doubtful  if  it  would  continue 
to  fill  as  rapidly  after  the  bailing  process  was  continued  for  a  short  time  The  nil 
is  of  light  gravity  and  very  good  quality.  The  Riley  well  was  drilled  nearly  a  half 
mile  north  of  the  San  Carlos  well  in  the  same  section  a  number  of  years  ago.  It 
started  near  the  top  of  the  steeply  dipping  Vaqueros  formation  and  went  down  for 
1200  to  1500  feet  without  reaching  the  base  of  the  formation  and  without  finding  oil. 
It  did  not  afford  a  test  of  the  area. 

"In  the  summer  of  1912  a  well  called  the  Snelling  well  was  started  about  200  feet 
northeast  of  the  old  San  Cailos  well.  It  begins  in  heavy  sandstone  beds  that  are 
believed  to  be  at  tine  very  base  of  the  Miocene  series.  The  monocline  here  dips 
approximately  50°  N.  When  visited  at  the  end  of  September,  1912,  the  well  had 
reached  a  depth  of  800  feet  through  the  imderlying  siliceous  Kreyenhagen  shale  At 
this  depth  the  bailer  was  bringing  up  oil  in  quantities  of  a  few  gallons  at  a  time. 
The  oil  is  of  a  dark-green  color  and  volatile,  soon  losing  some  of  its  lighter  con- 
stituents on  exposure.     An  analysis  of  the  oil  is  given  on  page  131. 

"About  two  miles  nortliwest  of  the  San  Carlos  well,  in  the  southern  part  of  Sec.  31, 
T.  16  S.,  R.  11  E.,  a  good  seep  occurs  in  sandy  and  gravelly  beds  interstratified  with 


72  CALIFORNIA   STATE    MINING   BUREAU. 

the  clay  of  the  Jacalitos  and  Etchegoin  formations.  This  seep  has  already  been 
described  (p.  135).  At  this  locality  tlie  Ashurst  Oil  Co.  put  down  two  or  three  wells, 
the  deepest  of  which  was  between  600  and  900  feet  deep  and  got  a  'showing'  of  oil 
and  gas  at  about  the  horizon  of  the  seep. 

"The  only  otlier  well  that  was  drilled  to  a  depth  of  more  than  a  few  feet  along 
this  belt  bordering  tlie  south  side  of  the  Vallecitos  was  the  Calistoga  well,  drilled 
many  years  ago  and  abandoned.  It  is  said  to  liave  gone  to  a  deptli  of  about  1100 
feet  in  the  clay  of  the  Jacalitos  and  Etchegoin  formations  on  the  terrace  in  Sec.  18, 
T.  17  S.,  R.  12  E.,  about  a  mile  southeast  of  John  Ashursfs  place,  and  to  have 
obtained  considerable  gas.  It  is  not  believed  to  have  reached  the  sands  of  the 
Vaciueros  formation  Tlie  Fresno-San  Benito  well,  which  was  drilled  in  Manoillas 
Canyon  farther  back  in  tlie  hills,  is  mentioned  on  page  166  in  connection  with  the 
discussion  of  the  Moreno  formation  The  Moreno  formation  is  separated  from  the 
Vaqueros  formation  by  a  great  tliickness  of  deeply  inclined  strata,  and  both  for  this 
reason  and  because  it  is  believed  to  be  absent  as  a  result  of  faulting  south  of  the 
western  half  of  the  Vallecitos  it  bears  little  relation  to  the  question  of  oil  occurrence 
along  the  south  side  of  tliis  valley  and  is  not  discussed  here. 

"From  the  foregoing  brief  account  of  the  wells  along  the  south  side  of  the  Vallecitos 
it  will  be  seen  that  none  of  them  has  afforded  a  real  test  of  the  area.  Most  of 
them  were  placed  too  near  the  outcrop  of  the  oil-bearing  beds  for  any  large  production 
to  be  reasonably  expected  and  the  better-located  ones  have  not  been  drilled  to  a 
sufficient  depth.  The  possibilities  of  the  area  are  practically  as  much  in  doubt  as 
if  tliese  wells  had  never  been  drilled.  The  conclusion  reached  from  the  geologic 
criteria  is  that  the  strata  stand  too  steeply  for  the  oil  to  be  retained  in  very  large 
quantities  or  for  their  deeper  portions  to  be  accessible  to  the  drill  at  reasonable 
depths  in  more  than  a  very  small  area.  The  beds  undoubtedly  contain  petroleum,  but 
tlie  oil  seems  to  have  been  disseminated  and  to  have  risen  freely  to  tiie  surface 
through  a  great  thickness  of  strata  rather  than  to  have  been  concentrated  in  any 
particular  porous  stratum  and  lield  there.  It  is  likely  that  wells  started  at  some 
distance  from  tlie  outcrop  and  striking  the  lower  beds  of  the  Vaqueros  at  a  con- 
siderable depth  would  give  a  small  production  of  oil,  especially  if  a  location  were 
chosen  where  the  monocline  is  not  as  steep  as  it  is  along  most  of  its  course.  It  is 
the  opinion  of  the  writers  that  althougli  such  wells  will  probably  be  able  to  produce 
oil  commercially  at  some  future  date,  the  present  cost  of  production  and  the  present 
price  of  oil  would  not  make  it  profitable.  Moreover,  it  is  possible  that  the  porous 
beds  are  occupied  by  water  at  no  very  great  depth  and  that  most  of  the  oil  is  near 
the   surface. 

"North    Flank   and    East    End    of  the   Vallecitos    Syncline.     General   features. 

"In  considering  the  north  flank  of  the  Vallecitos  syncline  attention  must  be  given 
both  to  the  Moreno  formation  and  its  associated  or  contained  sands  and  to  the  higher 
oil-bearing  zones  of  the  Kreyenhagen  and  Vaqueros.  Although  seeps  are  not  so 
numerous  along  this  side  of  the  valley  as  along  the  south  side,  indications  do  occur 
in  both  tile  lower  and  upper  zones  just  mentioned.  Along  the  western  part  of  the 
north  fiank  the  structure  is  similar  to  that  of  the  south  flank,  although  the  beds  do 
not  dip  quite  as  steeply.  The  general  dip  of  the  monocline  in  the  western  part  is 
between  40°  and  50°,  and  increases  slightly  from  a  point  near  the  axis  of  the  Ciervo 
anticline  outward,  so  that  the  Miocene  beds  dip  more  steeply  than  the  exposed  Moreno 
and  Panoche  formations.  Toward  the  east,  however,  the  reverse  is  the  case,  and  a 
decline  in  inclination  of  the  Tertiary  beds  to  angles  of  20°  and  15°  or  less  brings 
about  a  broadening  of  the  northern  portion  of  the  synclinal  basin.  Moreover,  the 
Vaqueros  formation  laps  unconformably  over  the  older  strata  and  dips  at  an  angle 
of  only  a  few  degrees  on  the  summit  of  the  first  ridge  north  of  the  valley.  It  would 
seem  that  formerly  the  Vaqueros  extended  back  to  the  north  a  considerable  distance 
at  this  low  angle,  over  the  truncated  edges  of  the  older  strata.  Just  south  of  the 
summit  of  the  ridge  bordering  the  north  side  of  the  Vallecitos  the  Vaqueros  formation 
slopes  more  steeply  beneath  the  syncline,  thus  forming  a  monoclinal  flexure  on  tiiis 
portion  of  the  north  flank.  The  attitude  of  the  hard  sandstone  beds  of  the  Vaqueros 
(lower  Miocene)  is  here  represented  fr.irly  well  by  the  surface  slopes  which  these 
beds  form.  Around  the  east  end  of  the  basin  the  gentle  inclination  of  the  Teitiary 
beds  continues,  until  they  turn  rather  sharply  into  the  steep  southern  Hank.  The 
surface  indications  of  oil  and  developments  that  have  taken  place  will  here  be 
described,  beginning  on  the  west. 

"West    Half  of   North    Flank  of  the  Vallecitos. 

"No  certain  evidences  of  oil  have  been  discovered  at  tlie  surface  in  the  Kreyenhagen 
shale  or  Vaqueros  formation  along  the  western  part  of  the  northern  flank  of  the 
Vallecitos  syncline,  but  seeps  occur  in  the  Moreno  formation  and  certain  wells  have 
obtained  oil  in  small  quantities  from  it.  These  wells  have  already  been  described  in 
connection  with  the  discussion  of  evidences  of  oil  in  the  several  formations. 

"These  seeps  appear  in  the  upper  beds  of  the  Moreno  in  the  canyon  of  the  Union 
Oil  Go's  wells  west  of  the  stage  road  to  Panoche,  which  follows  down  Gri.swold 
Canyon.  The  oil  is  of  dark  brown  color  and  is  comparatively  light  and  fluid.  It 
emits  a  pleasant  odor,  and  the  seeps  resemble  in  this  respect  and  in  general  appear- 
ance those  in  the  Oil  City  area  in  the  Coalinga  district.  In  fact,  the  formation  here 
is  the  continuation  of  that  at  Oil  City  and  the  oil  has  doubtless  had  the  same  origin. 
The  structure,  however,  is  somewhat  different,  for  in  the  Oil  City  locality  the  beds 
have  a  much  lower  dip  and  are  folded  into  an  anticline,  whereas  here  they  form  a 
steep  monocline.  The  character  of  the  oil  is  indicated  by  the  fact  that  at  these 
seeps  no  large  quaiUity  of  asphalt  has  been  deposited. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  73 

"The  analysis  of  the  oil  qviotod  on  page  123  shows  it  to  liave  a  specific  gravity 
of  0.9150  to  0.9090  (23°  to  24°  Baume)  and  to  be  intermediate  between  a  true 
paraffin  and  an  asplialt  oil.  In  this  nspeot  it  is  lilce  the  asplialtic  paraffin  oil  of 
Oil  City.  Tlie  sample  analyzed  was  not  fresh,  having  stood  in  an  open  shallow 
well  for  some  time;  hvnce  it  is  likely  that  the  oil  is  of  lighter  tiuality  wlien  it  issues 
from  tlie  rocks.  In  a  personal  rommimieation  tt)  tlie  writers,  Mr.  W.  W.  Orcutt.  of 
the  Union  Oil  Co.,  stated  tliat  tin-  oil  obtained  in  this  W(  11  (tlie  'Rebecca,'  a  dug  well 
about  80  feet  deep)  was  of  O.S433  (3t'>°  Baiime)  specific  gr.ivity,  and  tliat  about  5 
barrels  a  day  of  tliis  oil  was  pumped  out  witli  a  liand  pump  for  several  days  in 
succession.  Several  wells  were  drilled  in  tliis  vicinity  to  sliallow  deptlis  many  years 
ago,  but  llie  amount  of  oil  obtained  was  sm;ill  and  tlie  wells  were  abandoned  altliough 
a  man   was   kept  tliere  to  look  after  tlie  property. 

"Below  the  horizon  of  the  seeps  the  purple  shale  is  impregnated  with  oil  tlirough 
a  thickness  of  many  luindred  feet.  The  shale  is  aliout  1000  feet  thick  and  is  oily 
practically  throughout.  It  contains  a  number  of  large  Ic-nses  of  fine-grained  gray 
and  yellowish  sandstone  much  like  that  typical  of  the  concretionar.v  members  beli)w 
and  above,  and  these  lenses  mi.glit  be  expected  to  form  local  reservoii's  for  the  oil  at 
depths.  The  shale,  as  usual  in  rock  of  this  type  is  crushed  and  distributed,  but  the 
general  structure  is  that  of  a  monocline  dipping  about  4.5°  S.  The  concretionary 
sandstone  of  the  Martinez  (?)  immediately  overlies  tlie  shale,  and  signs  of  its 
being  slightly  impregnated  witli  oil  at  the  very  base  were  noted  locally. 

"The  conclitions  liere  are  very  much  the  same  as  in  the  area  of  the  siliceous  shale 
in  the  Kreyenhagen  and  Vaqueros  formations  on  the  south  side  of  the  valley,  already 
described.  It  is  probable  that  a  small  production  which  might  assume  economic 
importanc-e  at  some  future  time,  in  view  of  the  good  quality  of  the  oil,  would  result 
from  drilling  operations  in  the  shale  of  the  Mon  no  formation  here,  but  the  prospect 
does  not  seem  alluring  under  present  conditions.  It  is  not  unlikely  that  oil  might 
be  found  locally  in  sandstone  lenses  entirel.v  sealed  within  the  sliale 

"There  is  also  the  possibilit.v  of  wells  obtaining  oil  from  the  lower  part  of  the 
sandstone  that  overlies  the  shale,  and  if  serious  drilling  (jperations  were  to  be 
commenced  the  logical  jjlace  to  start  would  seem  to  be  at  a  point  south  of  the  outcrop 
of  the  Moreno,  where  the  base  of  the  sandstone  and  top  of  the  shale  would  bo 
reached  at  a  depth  ot  at  least  several  hundred  feet  It  is  believed,  however,  that  the 
steep  dip,  the  unifoi-m  monoclinal  structure,  and  the  dissemination  of  the  oil  througli 
so  great  a  thickness  of  beds  precludi'  the  hope  that  the  Moreno  and  the  Martinez  ( '.' ) 
formations  will  be  found  commerciallv  productive  in  the  near  future  The  area  to 
which  these  conclusions  apply  lies  in  the  NJ  Sec.  19,  the  S'  Sec.  18,  T,  16  S.,  R,  11  E., 
the  N'E.t  Sec.  24,  and  the  SJ  Sec.  13,  T.  16  S.,  R.  10  E.  Farther  east  tlie  purple 
shale  of  the  Moreno  formation  is  reduced  to  a  thin  zone,  and  in  that  direction  the 
outcrop  of  the  shale  itself  does  not  afford  promising  territory  for  the  production  of 
even  a  small  amount  of  oil  What  possibility  there  may  be  in  tliis  area  farther 
east  for  oil  gathering  from  below  into  the  concretionary  sandstone  overlying  the 
shale  can  not  be  forecast,  but  it  is  unlikely  that  any  important  quantity  gathers 
there.  In  a  westerly  direction  the  area  above  outlined  extends  to  Griswold  Canyon, 
the  western  limit  of  the  region  studied.  The  same  steep  monocline  of  the  Cretaceous 
and  later  beds  continues  westward  from  Griswold  Canyon  along  the  north  side  of 
the   valley   of   Pimental   Creek. 

"As  the  structure  of  the  Vafpieros  formation  is  very  similar  to  those  .iust  described, 
and  as  there  is  no  good  surface  sign  of  petroleum  in  it  or  in  the  Krey(>nhagen  shale, 
the  chances  for  oil  in  this  upper  zone  .ippear  even  slighter  than  those  for  oil  in  the 
lower  zone,  along  the  western  half  of  the  north  (lank  of  the  syncline.  At  one  point 
about  a  mile  east  of  Griswold  Canyon  an  oily  appearance  was  oljserved  in  the 
Vaqueros  formation  and  a  faint  petroleum  odor  obtained  This  was  just  enough  to 
indicate  tiiat  the  slighll.v  petroliferous  character  of  this  formation  persists  this  far 
west.  One  well — that  of  the  Sussex  Oil  Co. — was  drilled  in  this  region  between 
1910  and  1912  It  is  situated  near  the  center  of  Sec.  30,  T.  16  S.,  R.  11  E.  It 
started  in  the  steeply  dipping  clay  and  gravel  beds  of  tlie  Jacalitos  and  Etchegoin 
formations  and  is  reported  to  have  been  drilled  a  little  deeper  than  ISOO  feet  and 
to  have  obtained  signs  of  oil  and  gas  before  operations  were  stopped  At  this  depth 
it  had  probably  readied  the  middle  portion  of  the  Vaqueros,  but  it  could  not  have 
gone  as  far  as  the  base  of  that  formation,  which  should  have  been  reached  in  order 
to  make  an  adequate  test. 

"It  should  be  noted,  as  having  a  possible  bearing  on  the  question  under  discussion, 
that  an  intrusion  of  basalt  occurs  at  one  place  on  the  north  side  of  the  Vallecitos. 
It  penetrates  the  formations  at  least  as  far  up  as  the  summit  of  the  Vaqueros  sand- 
stone and  shale.  The  liasalt  outcrops  about  two  miles  north  of  the  divide  between 
the  two  arms  of  the  Vallecitos,  as  a  small  intrusion  p;irallel  to  the  bedding  near 
the  contact  of  the  Vaqueros  with  the  overlying  Jacalitos  and  Etchegoin  formations. 
It  is  the  onl.v  known  evidence  of  igneous  ;ictivity  later  than  Jurassic  or  eaily 
Cretaceous  in  a  wide  stretch  of  county  south  of  Panoche  Creek  and  east  of  Griswold 
Canyon.  Owing  to  its  local  nature  it  is  very  doubtful  if  it  has  seriously  affected 
the  oil-bearing  character  of  the  beds,  except  in  its  immediate  vicinity. 

"East    Half  of    North    Flank    of   the    Vallecitos. 

"The  problem  to  be  considered  in  the  area  along  tlie  eastern  portion  of  the 
north  Hank  and  around  the  east  end  of  the  fold  differs  from  that  presented  by  the 
more  westerly  area,  owing  to  the  lower  dip  in  the  Tertiary  beds  and  the  presence 
of  signs  of  oil  in  them  The  Moreno  and  the  formation  immediately  overlying  do 
not  assume  much  importance  here,  owing  to  the  lack  of  seeps,  as  well  as  to  the 
continuation    of    the    unfavorable    structure    of    the    area    farther    west.     Very    likely 


74  CALIFORNIA   STATE    MINING   BUREAU. 

these  beds  contain  a  little  oil  rlisseminated  tlirough  them,  but  unlrss  some  as  yet 
unsuspected  evidence  should  bo  brought  to  light,  it  seems  foolish  to  spend  money- 
drilling  to  or  into  the  Moreno  formation  here. 

"Structural  conditions,  although  not  highly  favorable,  suggest  that  oil  may  have 
collected  in  the  Vaqueros.  in  the  northea-stern  part  of  the  Vallecitos.  This  formation, 
moreover,  shows  undoubted  indications  of  oil.  The  area  has  certain  points  of 
resemblance  to  the  Westside  field,  which  make  it  worthy  of  careful  consideration. 
Tlie  Vaqueros  formation  here  is  the  same  formation  as  that  containing  the  main 
oil  sands  of  the  Coalinga  district  and  consists  of  similar  porous  sands.  It  overlies 
imconformably  the  siliceous  Kreyenhagen  shale,  the  supposed  original  source  of 
the  oil.  just  as  it  does  at  Coalinga.  It  lies  in  a  gently  dipping  monocline  on  the 
flank  of  a  synclino,  as  in  the  Westside  field.  It  shows  at  least  in  one  place  at 
the  surface  signs  of  petroleum  only  a  little  less  pronounced  than  those  in  the  Coalinga 
field,  and  it  is  overlain  here,  as  there,  by  relatively  impervious  clay  and  shale.  The 
main  dilTercnce  from  the  Westside  field  is  not  one  of  local  attitude  or  character 
of  the  beds  but  involves  a  consideration  of  the  broader  structural  relations,  which  are 
perhaps  of  greater  importance  than  the  similarities  above  mentioned  and  will  be 
discussed  in  the  final  paragraph  of  this  section  (p.  177),  where  conclusions  regarding 
the  possibility  of  this  area  and  of  the  Vallecitos  as  a  whole  will  be  expressed. 

"The  outcron  of  oily  sand  above  referred  to  occurs  on  Silver  Creek  in  the  basal 
beds  of  the  Miocene,  where  they  rest  on  the  truncated  edges  of  the  slightly  more 
steeply  dipping  Kreyenhagen  shale.  The  locality  is  on  the  northeast  edge  of  the 
Vallecito.<5.  in  the  western  part  of  the  SWJ  Sec.  .5,  T.  17  S.,  R.  12  E..  just  east  of  the 
New  Bedford  well.  The  same  beds  show  slight  evidences  of  being  oily  .at  other 
points  along  the  outcrops  to  the  northwest,  but  not  sufficiently  so  to  prove  the 
existence  of  a  considerable  petroleum  reservoir. 

"Tlie  Vaqueros  contains  beds  of  hard  sandstone  that  may  easily  be  traced  along 
their  outcrops,  because  tlicy  form  the  first  high  ridge  parallel  with  the  Vallecitos 
on  its  nortli  side.  The  formation  is  700  or  SOO  feet  thick  and  consists  of  a  lower 
zone  about  100  feet  thick  of  variable  sandy,  gr.avelly,  and  shaly  beds,  an  overlying 
zone  about  SO  feet  thick  of  siliceous  diatomaceous  shale,  and  an  iipper  portion  over 
.500  feet  thick  composed  chiefly  of  sandy  strata  with  some  interbcdded  shale  and 
containing  two  prominent  beds  of  hard  sandstone  in  its  centr.al  p.art.  each  about  100 
feet  thick.  ("See  the  tabulated  section  on  p.  86.)  The  lower  sandy  zone  has  the 
thickness  and  lithologic  qualities  that  would  make  it  an  excellent  reservoir  were  oil 
present  in  large  quantity.  Furthermore  the  overlying  flinty  shale  ought  to  serve 
as  an  imnervious  cap  to  prevent  the  oil  from  rising  into  higher  beds.  The  escape 
of  the  oil  along  the  bedding  planes  would  he  hindered  by  the  lowness  of  the  dip 
and  by  the  tendency  of  the  oil  to  seal  itself  in  by  the  deposition  of  solid  residue  near 
the  surface.  The  monoclin.al  dip  of  the  "\'aqueros  formation  within  .about  a  mile 
west  of  Silver  Creek  is  slightly  variable,  but  on  the  average  it  is  only  from  3°  to  8° 
toward  the  southwest.  Locally  there  is  a  tendency  toward  flattening,  affording  small 
wrinkles  that  might  be  a  factor  in  helping  to  hold  oil.  The  dip  of  the  monocline 
is  sufficiently  low  to  make  the  basal  portion  of  the  Miocene  beds  accessible  within 
a  reasonable  depth,  even  as  far  out  as  the  axis  of  the  Vallecitos  syncline. 

"About  2  mi'es  west  of  Silver  Creek  there  is  an  abrupt  steenening  of  dips  in  the 
Miocene  formations  along  the  edge  of  the  valley  to  20°,  30°  and  finally  4.5°  or  more. 
For  sever.al  miles  beyond  the  beds  preserve  a  low  dip  on  the  very  summit  of  the 
ridge,  but  they  fold  over  abruptly  into  the  steep  dips  on  the  south  side.  The 
steepness  of  these  dips,  combined  with  the  lack  of  evidence  of  any  appreciable 
quantity  of  oil  in  the  beds,  would  seem  to  leave  little  basis  for  expecting  them  to  be 
commercially  productive  west  of  the  very  small  area  of  low  dips  at  the  east  end 
of  the  north  flank,  already  described. 

"Around  V^e  east  end  of  The  Vallecitos  the  Tertiary  b?ds  are  brought  to  the 
surface  from  h°neath  the  valley  by  the  rising  end  of  the  syncline  and  occupy  crescent- 
shaped  belts  that  curve  aroimd  the  end  of  the  valley.  The  dip  of  the  beds  is 
everywhere  toward  the  valley  and  varies  between  5°  and  30°.  The  structure  is  not 
of  tiie  most  favorable  type  for  the  .iccnmulation  of  oil,  and  yet  it  is  such  that  a 
certain  amount  of  oil  would  be  expected  to  accumvilate  if  .any  existed  in  the  beds. 
The  shale  of  the  Vaqueros  lies  unconformably  upon  the  Kreyenhagen  shale,  as  in 
the  Coalinga  f^eld.  and  if  oil  were  present  in  the  shale,  it  shovild  rise  and  collect 
in  the  sandy  strata  overlying  its  truncated  edges,  making  itself  apparent  at  the 
outcrop.  No  seeps  or  other  surface  signs  of  oil  were  discovered  east  of  San  Carlos 
and  Silver  Creeks,  but  this  does  not  prove  that  they  do  not  exist,  for  the  beds  are 
locallv    masked    by   terr.ace    deposits. 

"The  following  wells  have  been  drilled  in  the  area  under  discussion  :  The  New 
Bedford  Oil  Co.'s  well,  in  the  NE.  i  SE.  J  sec.  6.  T.  17  S.,  R.  12  E.  :  the  Vallecitos 
Development  Co.'s  well,  in  the  NE.  }  sec.  12.  T.  17  S..  R.  11  E.  :  and  the  Range  Ifi 
Oil  Co.'s  well,  in  the  SE.  J.  sec.  3,  T.  17  S.,  R.  11  E.  The  New  Bedford  well  is 
situated  just  west  of  Silver  Creek,  near  the  outcrop  of  the  oil  sand  above  mentioned. 
It  starts  in  the  basal  portion  of  the  Vaqueros  .and  passes  through  the  oil  sand  that 
outcrops  on  Silver  Creek  at  a  depth  of  only  about  100  feet,  but  obviously  it  is  too  near 
the  outcrop  of  the  oil  sand  of  the  Vaqueros  to  obtain  .any  production  from  it.  Prac- 
tically the  whole  depth  drilled,  which  is  now  reported  as  more  than  3000  feet,  has 
been  below  the  oil  zone  of  the  Vaqueros,  the  zone  in  which  oil  shoiild  be  sought  for 
in  this  district.  At  about  IfiOO  feet  this  well  passed  through  a  6-foot  bed  of  coal  in 
white  sand,  evidently  coal-bearing  white  sandstone  of  the  Tejon.  Oil  is  said  to 
have  been  struck  at  a  depth  of  about  1700  feet,  but  it  has  not  been  possible  to  s\ib- 
stantiate  the  report.  At  a  depth  of  3000  feet,  the  well  should  be  in  the  midst  of  the 
Martinez  (?)  formation,  which  is  here  very  thick.  It  would  probably  require  a 
depth  of  at  least  1000  feet  more  to  reach  the  possibly  oil-bearing  beds  at  the  top  of 
the  Moreno  formation. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  75 

"The  well  of  the  Vallceitos  Development  Co.  was  started  in  1910  on  the  terrace 
a  mile  north  of  John  Ashiirst's  place.  It  started  in  the  lower  beds  of  the  Jacalitos 
and  Etchegoin  formations,  where  tlie  s.vnclinal  flank  has  a  low  dip,  and  was  excellently 
placed  to  test  the  possibilities  of  the  zone  at  the  base  of  the  Vaqueros.  Definite  infor- 
mation regardinK  the  results  obtained  are  not  available,  but  tlie  well  is  reported 
to  have  gone  to  a  depth  of  over  2,000  feet,  or  entirely  through  the  Vaqueros,  and  to 
have  found  some  oil  at  tlie  base  of  this  formation.  The  tools  brought  up  from  the 
bottom  were  said  to  be  covered  with  oil.  F'rom  the  fact  that  the  well  was  practi- 
c*ill.v  abandoned  in  1911  the  writers  infer  that  it  did  not  prove  a  success. 

"The  Range  16  Oil  Company's  well  is  situated  over  two  miles  farther  northwest 
and  starts  in  the  midst  of  the  .Jacalitos  and  Etchegoin  formations,  on  a  part  of  the 
synclinal  (lank  wliere  the  dip  is  steeper  than  farther  east.  It  was  drilled  in  1 010-11 
to  a  depth  of  2.300  feet,  without  obtaining  oil  in  any  important  quantity.  At  tliis 
depth  the  well  must  have  neai'ly  if  not  riuite  readied  the  base  of  the  Miocene  series. 

''Conclusions    Regarding   the    Vallecitos    District. 

"Consideiing  only  the  evidence  obtainalile  from  a  surface  stud.v,  the  area  described 
in  the  paragraphs  just  preceding — -that  is,  the  east  end  of  the  north  flank  and  the 
curving  east  end  of  the  syncline — seems  a  faii'ly  promising  place  to  search  for  oil 
and  tlie  most  promising  portion  of  the  Vallecitos  district.  The  amount  of  oil  that 
comes  to  the  surface  at  various  points  in  The  Vallecito.s,  and  the  resemblance  of  the 
stiaicture  in  the  east  end  of  the  valley  to  that  of  the  Westside  field,  make  it  not 
unreasonable  to  suppose  that  oil  may  have  collected  here  in  fairly  good  quantity. 
This  conclusion  was  expressed  in  the  preliminary  report  on  the  Cantua-Panoche 
region.'  That  report  was  prepared  before  any  wells  had  been  started  to  test  the 
sands  in  the  Vaqueros  formation  at  tlie  east  end  of  The  Vallecitos,  and  it  suggested 
a  small  area  at  that  end  of  the  valley  as  offering  a  reasonal)lo  location  for  the  drill- 
ing of  a  test  well.  Such  a  test  has  subsequently  been  made  by  the  well  of  the 
Vallecitos  Development  Co.  before  mentioru'd.  and,  altliough  it  has  not  been  possi'ole 
to  ascertain  defmitel.v  the  results  obtained  in  this  well,  numerous  indications  point  to 
its  having  l)een  a  failure.  The  writers  believe  it  likely  that  below  the  surface  the 
Vaqueros  formation  does  not  contain  as  mucii  oil  as  one  might  be  led  to  believe  by  a 
comparison  of  tlie  surface  evidences  of  oil  in  this  region  with  similar  evidences  in 
regions  that  have  been  fomid  highly  productive.  As  stated  in  the  preliminary  report, 
the  drill  alone  can  determine  with  certainty  whether  oil  exists  in  paying  fiuantities 
in  the  beds  which  at  the  surface  show  traces  of  oil.  Tlie  opinion  at  present  held  liy 
the  writers  is  based  on  the  apparently  unfavoralile  evidence  afforded  on  this  point 
b'y  the  well  previously  referred  to,  and  on  a  more  general  consideration  of  the  condi- 
tions governing  oil  accumulation  along  the  western  border  of  the  San  Joaquin  Valley 
or  from  any  other  outside  territory  tliat  might  be  trilmtary  to  its  oil  and  water  supply 
points  to  tlie  prolialulity  that  no  very  important  peti'oleum  accumulations  are  to  be 
looked  for  in  this  valley.  The  writers  would  not  recommend  the  expenditure  of  any 
mone.v  in  further  attemnts  to  olitain  paying  quantities  of  petrohHim  anywhere  in  the 
Vallecitos  district,  until  the  value  of  oil  has  increased  or  the  expense  of  operating 
decreased  to  such  a  point  that  risks  could  be  taken  for  the  sake  of  obtaining  occa- 
sional very  small  producing  wells. 

"Crest  and   Flanks  of  the  Ciervo  Anticline. 

"The  Ciervo  anticline  is  an  oblique  offshoot  of  the  main  structure  of  the  Diablo 
Range,  similar  in  type  to  the  Coalinga  anticline.  It  is  probable  that  in  the  past  history 
of  the  region,  in  late  Tertiary  or  early  Quaternary  time  the  summit  of  the  anticline 
was  covered  throughout  areas  many  square  miles  in  extent  by  the  Tertiary  formations 
and  that  oil  accumulated  in  large  quantities  along  it.  During  the  course  of  time,  how- 
ever, the  oil-bearing  formations,  together  with  their  stores  of  oil,  liave  been  worn 
awav  from  the  ma.ior  portion  of  the  antiiline,  leaving  the  underlying  unproductive 
sandstone  of  the  Panoche  formation  (Upper  Cretaceous)  exposed  in  a  wide  belt  on 
either  side  of  the  axis.  Tlie  only  place  where  beds  as  young  as  the  lower  oil-bearing 
zone  of  this  region  remain  over  the  axis  of  the  fold  is  at  its  east  end,  where  it 
plunges  steeply  and  merg(  s  with  the  monocline  of  tlie  foothills.  At  this  place  it  is 
covered  by  shale  of  the  Moreno  formation,  the  overlying  concretionary  sandstone 
and  clay  shale  of  the  Martinez  (?)  formation,  and  the  succeeding  Tejon  formation. 
The  area  embracing  this  end  of  the  anticline  is  the  one  which  will  be  discussed  here. 

"The  structure  of  this  area  is  similar  to  that  of  the  plunging  end  of  the  Coalinga 
anticline,  which  has  proved  so  productive,  and  the  chance  for  the  presence  of  oil 
here  deserves  careful  consideration.  The  most  important  differences  between  this 
area  and  that  on  the  nose  of  the  Coalinga  anticline  are  as  follows:  The  Ciervo 
anticline  is  not  so  extensive  a  fold  as  that  at  Coalinga.  It  stops  short  without  reaching 
the  San  Joaquin  Valley  and  plunges  abruptly  without  affecting  strongly  the  Tertiary 
beds  of  the  foothills,  whereas  the  Coalinga  fold  continues  on  for  many  miles  into  the 
valley  with  a  perfect  cover  of  Tertiary  formations.  On  the  Ciervo  fold  only  one  of 
the  shale  formations  of  organic  origin  (the  Moreno,  Upper  Cretaceous)  is  present  and 
the  evidences  of  oil  in  this  formation  are  not  pronounced  ;  on  the  Coalinga  anticline 
the  two  oil-bearing  shale  formations  are  present,  and  both  give  at  their  outcrops 
unmistakable  evidence  of  their  petroliferous  character.  Moreover,  on  the  Ciervo 
fold  the  Moreno  formation  outcrops  ,iust  at  the  point  where  the  fold  plunges  steeply 
to  its  termination,  instead  of  continuing  along  the  axis  at  a  relatively  low  and 
constant  dip  beneath  tlie  later  formations.  These  differences  are  all  unfavorable  to 
the  Ciervo  area  when  its  possibilities  of  yielding  oil  are  compared  witli  those  oi  the 
Coalinga  fold.     They   lead    to   the   conclusion    that    the   Ciervo    area,   if   productive   at 


'Anderson,  Robert.     U.   S.  Geol.  Survey,     Bulletin  431.     Pp.   76-77.   1910. 


76  CALIFORNIA   STATE    MINING    BUREAU. 

all,  will  be  very  much  less  so  than  thf  Coalinga  anticline.  Owing  to  the  limitation 
as  regards  possible  oil-bearing  formations  on  this  fold,  the  proper  comparison  to 
be  made  is  witli  tlie  Oil  City  field  and  with  the  sands  in  the  Martinez  (?)  and  Tejon 
formations  in  tlie  Coalinga  district.  The  result  of  this  comparison  is  likewise  unfav- 
orable to  the  Ciervo  field,  and  yet  there  is  enough  similarity  to  suggest  the  possible 
existence  of  a   commercial   quantity  of  oil    here. 

"Tlie  purple  shale  of  the  Moreno  formation  is  exposed  in  an  area  of  several 
s(iuare  miles  near  the  axis  of  the  Ciervo  anticline  in  Sees.  14,  1.5,  21  and  23,  T.  16  S., 
R.  12  E.,  and  passes  beneath  later  beds  along  the  summit  of  the  fold  in  the  SWJ 
Sec.  24,  the  NWJ  Sec.  25  and  the  NJ  Sec.  26  of  the  same  township.  The  area 
near  the  summit  of  the  fold  in  which  the  shale  of  the  Moreno  would  be  within  reach 
of  a  drill  or  at  a  depth  of  not  more  than  3000  feet  below  the  surface  is  approximately- 
outlined  by  a  red  line  on  the  geologic  map  (PI.  1).  Several  doubtful  factors,  such 
as  abrupt  variation  in  thickness  of  the  different  formations  and  uncei'tainty  as  to 
the  attitude  of  tlie  beds,  make  the  drawing  of  such  a  line  difficult,  and  it  is  shown 
merely  for  the  purpose  of  giving  a  rough  indication  of  the  more  important  part  of 
the    area    here   under    discussion. 

"If  any  appreciable  ciuanlity  of  oil  is  present  in  the  Moreno  formation  the  condi- 
tions of  structure  in  this  area  make  it  probable  that  productive  wells  could  be 
obtained  by  drilling  down  to  included  lenses  of  sand,  or  to  the  sandstone  beds  that 
overlie    the    shale. 

"Mention  has  previously  been  made  (in  the  section  dealing  with  oil  indications 
in  the  several  formations)  of  the  oily  sands  discovered  at  certain  places  in  the 
Moreno  formation  near  the  axis  of  the  Ciervo  anticline.  In  addition  the  shale  gives 
the  appearance  of  having  been  thoroughly  impregnated  witli  petroleum.  It  is 
characterized  by  the  blackish-brown  discoloration  and  strong  sulpliurous  odor  that 
seem  to  result  from  the  presence  of  oil  in  shale  of  this  type  in  many  places.  The 
oil  sands  easily  escape  notice  owing  to  the  weathered  nature  of  tl;e  exposures,  but  tiie 
appearance  of  fresh  specimen^  of  the  rock  leads'  to  the  belief  that  a  lar.ge  part  of 
tlie  formation  has  previously  been  and  may  still  be  soaked  with  oil  and  tliat  a 
considerable  amount  of  free  oil  might  be  found  in  the  beds  at  greater  depth,  away 
from  tlie  surface  zone  of  weathering  and  evaporation.  The  light  oil  found  in  the 
purple  shale  at  Oil  City  and  at  the  Union  wells,  north  of  the  west  end  of  The 
Vallecitos.  wliich  appears  to  be  f  haractei  istic  of  this  horizon,  is  of  a  type  that 
would  not  be  expected  to  leave  at  the  surface  as  marked  evidences  of  its  presence 
as  the  asphalt  oil  in  the  Miocene  formations  of  the  Coalinga  district  and  other 
parts   of   California. 

"If  the  formation  contains  as  large  an  amount  of  oil  as  is  believed,  the  question 
remains  whether  the  oil  is  too  widely  disseminated  through  many  hundred  feet  of 
beds  to  be  obtainable  in  commercial  quantity,  or  whether  some  of  it  has  accumulated 
in  reservoirs  that  may  be  profitably  tapped.  There  can  be  no  doubt  tliat  a  large 
amount  has  been  lost  by  dissemination  thi'ough  the  beds  and  esc^ipe  at  the  surface, 
as  is  attested  by  the  prevalence  of  the  oil  discoloration  throughout  tlie  formation. 
But  it  is  an  important  fact  that  thick  lenticular  beds  of  porous,  fine-grained  sand 
wliicli  ought  to  be  good  reservoirs  are  included  in  the  shale,  and  it  is  higlily 
probable  that  much  oil  has  been  absorbed  by  these  lenses  and  retained  in  them. 
The  lenses  are  not  confined  to  any  particular  part  of  the  shale  but  occur  in  its  upper 
as  well  as  its  lower  portion  and  would  be  found  somewhere  witliin  the  shale  in 
any  section  tliat  might  be  made  of  it.  Some  of  the  lenses  attain  a  thickness  o"' 
100  feet  or  more.  The  body  of  oil-bearing  beds  of  which  the  purplish  shale  is  the  chief 
eonstituent  is  likewise  overlain  by  sandy  strata  in  whjeli,  it  might  be  exoected,  oil 
would  accumulate.  Wells  drilled  through  the  later  becls  at  a  considerable  distance 
from  the  outcron  of  the  purp'e  shale  would  probably  reach  the  shale  and  its  included 
sands  at  a  depth  at  which  the  petroleum  contents  would  be  sealed  in  and  preserved 
intact.  A  good  situation  for  a  test  well  is  about  2  miles  northwest  of  Ciervo 
Mountain.' 

"The  dip  of  the  beds  in  the  Ciervo  Mountain  region  is  low  and  the  structure  is 
undulating,  and  it  is  not  impossible  that  some  of  the  minor  folds  might  aid  in  the 
concentration  and  confinement  of  a  local  body  of  oil.  In  this  connection  it  is  worthy 
of  note  that  a  number  of  small  faults  in  the  Tertiary  formations  in  this  region 
have  not  brought  to  light  any  oil  through  seepage ;  but  in  the  opinion  of  the 
writers  this  fact  does  not  carry  great  weight  as  against  the  favorable  conditions 
mentioned.  The  conclusion  is  that  the  area  on  and  ad.iacent  to  the  Ciervo  anticline 
offers  possibilities  that  should  be  tested.  It  is  believed  that  a  well  drilled  near  the 
summit  of  the  anticline,  as  sugested.  would  liave  a  chance  of  obtaining  a  light  oil 
In  paying  quantity,  but  the  risk  of  failure  would  be  great  and  the  likcliliood  would 
be  of  a  small  production,  if  any,  being  obtained.  This  much,  at  least,  may  be  said — 
that  the  conditions  are  mucli  more  favorable  than  those  in  many  places  where 
'wild-caf   wells  are  being  drilled   in   C;ilifornia   outside  of  the  developed   fields. 

The  Extreme  Southwestern  Portion  of  the  County. 

This  area  consists  of  the  territory  south  of  the  town  of  San  Benito 
and  includes  the  upj^er  portions  of  the  San  Benito  Valh^y  and  the  areas 
around  Toro  Creek.  Bitterwater  Creek  and  Lewis  Creek. 


'Since  the  publication  of  the  above  report  the  Standard  Oil  Company  drilled  a 
well  in  Sec.  25,  T.  16  S..  R.  12  E.,  about  3  miles  northwest  of  Ciervo  Mountain  and 
about  a  mile  east  of  the  San  Benito  County  line  in  Fresno  County.  A  depth  of 
SS69   feet  was  reached  and  no  indications  of  oil  were  encountered. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  77 

The  (liuniiiant  structiifal  fcaTurc  of  this  rcKioii  is  the  Sail  Andreas 
fault,  whieh  runs  south  alonu'  San  J^enito  Creek  as  far  as  the  town  of 
San  Benito  where  it  crosses  a  h)\v  divide  into  the  Rabbit  Valley  and  from 
tliere  it  runs  down  Ritterwater  Creek  to  its  junr-tion  witli  Lewis  Creek 
and  then  eontinues  soutliward  up  Lewis  Creek. 

ICast  of  the  San  Andreas  fault  the  formations  exposed  are  sands, 
gravels  and  clays  of  the  P^tehegoin  and  Jacalitos  formations,  which  rest 
on  the  east  ai^niinst  the  Franciscan.  In  the  fault  zone  of  tlie  San 
Andreas  fault,  which  averages  about  one  mile  in  width,  the  faulting- 
has  exposed  beds  of  Franciscan  and  Cretaceous  age,  together  with 
masses  of  granite  and  ancient  crystalline  metamorphics.  West  of  the 
San  Andreas  fault  the  foi-matioiis  consist  of  beds  of  sand  and  gravels 
of  the  Paso  Kobles  forn)ation  with  a  thickness  of  about  2U0  feet.  Below 
the  Paso  Robles  is  about  3000  feet  of  the  Santa  Margarita  formation 
consisting  of  beds  of  medium  coarse  white  sand  and  abont  1000  feet  of 
sandy  diatomaceous  shale.  This  shale  is  found  near  the  bottom  of  the 
formation  and  is  the  source  of  the  oil  found  in  this  area.  Along  its 
northwestern  edge  in  the  vicinity  of  the  Pinnacles,  the  Santa  Margarita 
rests  against  the  eroded  surface  of  the  crystalline  rocks  of  the  Gavilan 
Range. 

An  area  of  granite  probably  belonging  to  tlie  batholithic  mass  of  the 
Gavilan  Range,  outcrops  along  San  Lorenzo  Creek  just  west  of  Lonoak 
and  the  Santa  ^largarita  sands  rest  unconformably  against  its  edges. 

Indications  of  i)etroleum  are  found  in  seeimges  along  the  San  Andreas 
fault  zone  in  Lewis  Creek  and  at  the  contact  of  the  Santa  ]\largarita 
with  the  granite  in  the  vicinity  of  Lonoak  and  San  Lorenzo  Oeek. 
Apparently  on  account  of  unfavorable  structure,  the  oil  has  tended  to 
collect  along  faults  and  at  the  contacts  with  the  igneous  rocks. 

Tlu'  region  is  apparently  unfavorable  for  the  accumulation  of  petro- 
leum in  commercial  quantities.  This  statement  is  based  on  the  follow- 
ing facts:  (1)  The  structure  is  unfavorable  (See  Sec.  EF,  Fig.  6). 
(2)  The  source  of  the  petroleum  is  the  diatomaceous  shale  of  the  Santa 
iMargarita,  which  is  too  limited  in  thickness  and  extent  to  form  much 
oil.  (3)  Twenty  wells  have  been  drilled  in  the  area  and  none  showed 
sufficient  production  to  be  of  commercial  value  (list  of  wells  is  given 
below.) 

The  greater  portion  of  the  district  has  been  mapped  and  examined  for 
oil  possibilities,  both  by  the  State  iMining  Bureau^  and  the  U.  S.  Geologi- 
cal Survey.-  The  report  by  the  State  covers  the  southwestern  part, 
while  that  of  the  Geological  Sui'V(\v  practically  covers  the  entire  area 
in  detail.  Both  reports  contain  a  list  of  the  wells  drilled,  together  with 
areal  maps. 

Following  is  a  portion  of  the  Geological  Survey's  report,  dealing  with 
the  area  under  discussion,  and  also  including  that  part  of  ]\lonterey 
Countv  east  of  King  Citv  and  alonu'  the  Peachtree  and  Lewis  Creek 


'California  State  Mining  Bureau.  Bull.  69,  1914.  Petroleum  lndu.strv  of  California. 
By  R.  P.  McLaughlin  and  C.  A.  Waring.      Pp.  418-428,  plate  IV  in  folio. 

^United  States  Geological  Survey.  Bull  581-D,  1914.  Geology  and  Oil  Prospects  of 
the  W'altham,  Priest,  Bitterwater  and  Peachtree  valleys.  By  R.  W.  Pack  and  W.  H. 
English. 


78  CALIFORNIA   STATE   MINING  BUREAU. 

vallej-s,  Sec.  EF,  Fig.  6  is  adapted  from  this  report  and  shows  the  gen- 
eral structure: 

"Bitterwater  and    Peachtree  Valley   and    Foothills  to   the   West.     Geology. 

"West  of  the  San  Andreas  fault  zone  the  beds  mapped  as  upper  Miocene  rest 
directly  upon  the  eroded  surface  of  the  granite.  In  llie  area  shown  on  tlie  map  these 
beds  have  a  maximum  thielcness  of  about  3300  feet  and  comprise  two  formations,  of 
which  the  lower,  made  up  of  sand,  clay,  gravel,  and  diatomaceous  shale  and  filled 
with  marine  fossils,  is  believed  to  be  the  equivalent  of  the  Santa  Margarita  forma- 
tion, and  the  upper,  composed  of  material  that  was  probably  laid  down  in  lakes  or 
subaerially,  is  the  equivalent  of  the  Tulare  formation.  West  of  Peachtree  Valley 
the  upper  of  the  two  formations  is  relatively  unimportant,  appearing  only  in  isolated 
areas  along  the  crests  of  the  ridges  as  a  cap  less  than  200  feet  thick.  The  bods 
that  are  comprised  in  the  formation  that  is  considered  the  equivalent  of  the  Santa 
Margarita  are  variable  in  character,  ranging  from  coarse  conglomerate  to  fine 
diatomaceous  shale,  but  for  the  most  part  are  fine  grained.  Near  Lonoak  and  in 
Bitterwater  Valley  the  lower  1000:+^  feet  is  composed  of  diatomaceous  shale,  which 
forms  prominent  white  outcrops  that  are  especially  noticeable  about  2  miles  north- 
west of  Lonoak  postofflce.  Sliale  of  this  type  forms  the  lower  part  of  the  Tertiary 
along  the  west  side  of  Bitterwater  Valley,  in  the  north  end  of  Mustang  Ridge,  in 
small  areas  near  the  east  corner  of  the  Peachtree  ranch,  and  in  much  of  the  Topo 
rancli  northwest  of  the  area  mapped.  In  many  other  parts  of  the  region,  however, 
sandy  or  even  gravelly  beds,  such  as  those  exposed  near  the  asphalt  quarry  west 
of  Lonoak,  rest  upon  the  granite.  Practically  no  diatomaceous  shale  appears  resting 
upon  the  granite  near  its  exposures  in  small  areas  4  miles  southwest  of  Lonoak. 
The  variability  in  the  lithology  of  the  lower  part  of  the  Tertiary  is  well  shown 
along  the  north  side  of  San  Lorenzo  Creek  west  of  the  granite  that  is  exposed  at 
the  edge  of  the  area  mapped.  Possible  explanations  of  the  variability  in  the  thickness 
of  the  diatomaceous  shale  appear  to  be  (1)  that  the  Tertiary  beds  wtM-e  laid  down 
upon  a  very  uneven  surface  of  granite  and  that  in  parts  of  the  region  the  lower 
beds  were  not  deposited;  (2>  that  the  sliale  actually  grades  laterally  into  coarser 
materials;  (3)  that  the  diatomaceous  shale  is  older  than  the  clay  and  shale  and  is 
separated  from  them  by  an  unconformity.  The  most  probable  explanation  seems 
to  be  that  the  variability  in  the  thickness  of  the  shale  is  due  both  to  lateial  variation 
in  character  and  to  the  uneven  surface  upon  which  it  rests.  Sandy  beds  intercalated 
witli  the  diatomaceous  sliale  contain  fossils  apparently  of  precisely  the  same  type 
as  those  in  the  overlying  sandy  beds,  and  it  seems  improbable  that  any  considerable 
time  intervened  between  the  deposition  of  the  two  divisions.  Tlie  presence  or  absence 
of  tlie  diatomaceous  shale  is  of  considerable  importance,  for  the  seeps  of  oil  appear 
only  in  those  areas  where  it  has  considerable  thickness. 

"The  Tertiary  strata  that  cover  the  granite  have  not  been  deformed  to  any  very 
marked  degree  west  of  the  San  Andreas  fault  zone.  West  of  Peachtree  Valley 
nearly  to  the  edge  of  the  area  mapped  this  cover  may  be  thought  of  as  a  sheet, 
very  slightly  wrinkled  along  irregular  lines  and  in  general  dipping  slightly  toward 
the  northeast.  P^arther  west  the  dip  changes ;  along  the  edge  of  Salinas  Valley  it 
is  in  general  toward  the  west,  cai-rying  the  beds  beneath  the  valley.  Between 
Peachtree  Valley  and  the  San  Andreas  fault  zone  is  a  shallow  syncline,  which  the 
writers  have  termed  the  Peachtree  syncline.  This  fold  starts  near  the  center  of 
the  Peaclitree  ranch  and  continues  northwest  through  the  Topo  ranch,  beyond  the 
area  mapped.  The  east  flank  of  this  syncline  is  terminated  by  the  San  Andreas 
fault  zone,  along  which  the  beds  of  diatomaceous  shale  in  the  lower  part  of  the 
later  Miocene  formations  are  to  tilted  that  they  are  nearly  vertical.  North  of  Lonoak 
the  southwest  flank  of  the  syncline  merges  with  the  area  of  low  irregular  dips 
along  the  foothills  east  of  the  Salinas  Valley,  but  along  the  Peachtree  Valley  it  is 
apparently  terminated  by  a  fault.  It  is  in  this  synclinal  basin  that  most  of  the 
drilling  for  oil  has  been  done.  Along  the  San  Andreas  fault  a  zone  varying  from 
three-quarters  to  1  mile  in  width  is  traversed  by  innumerable  faults  and  the  rocks 
are  greatly  shattered.  In  this  zone  rocks  of  the  Franciscan  and  later  formations  are 
intermingled  in  irregxilar  masses,  and  along  the  west  side  steeply  tilted  beds  of 
diatomaceous  shale  occur.  Through  this  zone  of  fracture  oil  contained  in  the  rocks 
has  found  an  easy  passage  to  the  surface.  Several  wells  have  been  drilled  along  it, 
but  none  of  them  have  found  any  considerable  reservoir  of  oil. 

"Surface   Indications  of  Petroleum. 

"In  several  places  in  Bitterwater  and  Peachtree  valleys  oil  impregnates  the 
surficial  sandy  beds  that  lie  in  the  San  Andreas  fault  zone  oi-  that  rest  upon  the 
granite.  The  largest  of  these  outcrops  occurs  at  the  Mylar  asphalt  quarry,  in  Sees. 
14  and  15,  T.  19  S.,  R.  9  E.,  about  2  miles  west  of  Lonoak.  The  basal  2.")  to  50  feet 
of  the  later  Miocene  here  is  a  coarse,  arkosic  sand  or  grit  that  was  evidently 
derived  from  the  granite  upon  which  it  rests.  The  outcrops  of  this  sand  for  a 
distance  of  about  one-half  mile  are  impregnated  with  tarry  oil  or  asphalt,  the 
amount  contained  varying  from  place  to  place.  Where  the  outcrops  are  weathered 
and  unbroken  the  sand  is  light  brown  and  friable,  but  in  the  newer  faces  of  the 
quarry  tlie  sand  is  plastic  from  the  amount  of  tar  it  contains,  and  in  one  place  thick 
oil  slowly  oozes  out  along  its  contact  with  the  underlying  granite.  The  oil  sand 
or  asphalt  is  quarried  from  time  to  time  and  used  in  repairing  the  roads  about 
King  City.  Most  of  the  sand  is  of  medium  coarse  grain,  and  the  material  is  used 
directly  upon  the  roads  without  the  addition  of  more  sand. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  79 

"Oil-saturated  sands  outcrop  at  two  i.laoes  near  the  southeast  corner  of  the 
Peachtree  ranch,  in  what  corresponds  to  tlie  SEJ  Sec.  22  and  the  SWi  Sec.  25  T.  20  S., 
RUE  \t  the  first-named  locality  a  massive  sand.stone  that  stands  almost  vertical 
occurs  on  'the  west  side  of  an  area  of  much  contorted  diatomaccous  shale,  ihe 
relationship  of  the  sandstone  and  shale  is  not  entirely  clear,  as  the  rocks  are  con- 
siderably faulted,  but  the  sandstone  is  believed  to  be  stratigraplueally  above  most 
or  possibly  all  of  the  shale.  The  sandstone  is  impregnated  with  heavy  od,  which 
slowly  seeps  out  in  the  bottom  of  one  of  the  steep  arroyos.  About  1.^  miles  southeast 
of  this  seep  a  sandstone  50  to  60  feet  thick,  bedded  with  the  diatomaceous  shale 
that  occurs  near  the  base  of  the  Tertiary,  is  impregnated  with  oil.  This  bed  appears 
to  be  a  sandv  lens  in  the  upper  part  of  the  diatomaceous  shale.  It  lies  at  the 
western  edge  "of  the  San  Andreas  fault  zone,  is  much  fractured,  and  is  truncated 
on    the    east    by    a    fault    that    brings    it    into    contact    with    the    clay    in    the    iulare 

"Where  the  San  Andreas  fault  crosses  Alvarez  Creek,  in  Sec.  32,  T.  IS  S.,  R-  10  E., 
an  outcrop  of  much  fractured  coarse  arkosic  sandstone  in  the  Tulare  formation  is 
stained   by  petroleum  and  wells  less  than   100   feet  deep  sunk  here  have  yielded  a 

little   light-gravity  oil.  .  ,      .      c.        oa    n-    i-  ci     t>    e  v 

"About  13  miles  due  north  of  King  City,  approximately  in  Sec.  29,  1  U  ^  ,  K.  !>  b.,. 
at  the  Matthews  asphalt  quarry,  a  bituminous  sandstone  outt'rop  lies,  like  that  at  the 
Mylar  quarry  near  Lonoak,  between  outcrops  of  granite  and  of  diatomaceous  shale. 
This  sandstone  mav  underlie  the  diatomaccous  shale,  as  was  suggested  by  Eldriage, 
but  as  the  oil  sand  is  limited  to  the  small  gulch  tributary  to  Chalone  Creek  and 
contains  besides  granitic  material  an  appreciable  number  of  diatomaceous  shale 
fragments,  the  writers  suggest  tliat  it  is  jjrobably  a  stream  terrace  deposit  impreg- 
nated with  and  cemented  by  thick  tarry  oil  that  seeped  out  of  the  lower  part  ot  the 
diatomaceous  shale.  The  beds  of  sand  and  gravel  impregnated  with  oil  are  or 
very  uneven  grain  and  on  the  whole  arc  much  coarser  than  tliose  at  the  Mylar  quarry. 

"Wells   Drilled   for   Oil. 

"The  following  wells  have  been  diilled  loi  dil  in  and  near  Bittervvator  and 
Peachtree  valleys ; 

Nonpareil  No.   1,   Sec.   32,   T.   18  S.,  R.   10  E. 

Nonpareil  No.  2,  Sec.  32,  T.   18  S.,  R.   10  E. 

Nonpareil  No.   3,   Sec.   32,  T.   IS   S.,   R.   10  E. 

Lonoak  No.   1,   Sec.   7,  T.   19   S..   R.   10   E. 

Lonoak  No.  2,  Sec.  31,  T.  18  S.,  R.  10  E. 

Alvarez  No.   1,  Sec.  33,  T.  KS  S.,  R.   10  E. 

I>e  Franc  No.  1  (Standard  Oil  Co.).  Topo  ranch,  in  wliat  corresponds  to  Sec.  33, 
T.   17  S.,  R.  9  E. 

Tompkins  No.   1    (Standard  Oil  Co.),  Sec.  19,  T.   li)  S.,  R.  10  E. 

Tompkins  No.  2    (Standard  Oil  Co.),   Sec.   19,  T.   19  S.,  R.  10  E. 

Landrum  No.  1    (Standard  Oil  Co.),  Sec.  28,  T.  19  S.,  R.  10  E. 

Doheny  well.  Sec.  14  or  15,  T.  19  S.,  R.  9  E.  <,         o . 

Miller  No.  1  (Union  Oil  Co.),  Peachtree  ranch,  in  what  corresponds  to  Sec.  ii, 
T.  20  S.,  R.  10  E. 

Salinas  No.  1,  Sec.  9.  T.  19  S.,  R.  10  E. 

"The  Nonpareil  wells  were  drilled  about  13  years  ago  near  the  seep  where  the 
San  Andreas  fault  crosses  Alvarez  Creek.  Previous  to  the  drilling  of  the  main 
wells,  two  wells  were  drilled  by  hand,  the  deeper  of  which  is  said  to  have  obtained 
light-gravity  oil  at  60  to  70  feet.  At  the  time  of  the  writers'  visit  it  had  caved 
below  the  55-foot  depth  and  was  dry  of  oil,  although  containing  considerable  gas. 
Of  the  three  larger  wells.  No.  1  is  said  to  have  reached  a  deplli  of  1038  feet  without 
obtaining  more  than  a  trace  of  oil.  Well  No.  2  was  drilled  653  feet  and  obtained 
oil  between  400  and  520  feet.  Oil  now  stands  in  the  hole,  but  the  well  has  never 
produced.  Well  No.  3  reached  a  depth  of  1300  feet,  having  been  drilled  through 
'a  great  mixture  of  rocks,'  but  obtained  no  oil. 

"Lonoak  well  No.  1  was  sunk  about  2700  feet  and  is  .said  to  have  reached  granite 
at  that  depth  without  having  encountered  a  trace  of  oil.  Well  No.  2  reached  a 
depth  of  3009  feet,  getting  a  little  tarry  oil  at  600,  800,  and  1800  feet.  A  few 
barrels  of  oil  is  said  to  have  been  pumped. 

"The  Salinas  well  is  .said  to  have  been  drilled  to  450  feet  and  at  that  deptn  to 
have  found  a  little  very  heavy  oil  like  that  in  Lonoak  well  No.  2. 

"The  Dohenv  well,  near  the  southwest  corner  of  Sec.  14,  T.  19  S.,  R.  9  E..  starts 
about  750  feet  south  of  the  outcrop  of  the  oil  sand  at  the  Mylar  asphalt  quarry-  It 
is  said  to  have  reached  the  granite  at  900  feet  without  having  found  oil.  The 
lack  of  success  of  this  well  is  striking  and  shows  the  local  character  of  the  oil 
sand   that  is  quarried  as  asphalt. 

"The  Alvarez  well  was  started  a  few  hundred  feet  south  of  the  oil  Nonpareil 
wells  and  drilled  to  a  depth  of  900  feet  but  obtained  no  oil. 

"The  Le  Franc  well  of  the  Standard  Oil  Co.,  at  the  head  of  Bitterwater  Valley, 
within  a  few  hundred  feet  of  the  San  Andreas  fault  line,  was  drilled  to  a  depth  of 
more  than  2000  feet.  It  is  said  to  have  penetrated  considerable  oil  sand  but  produced 
no  oil.  The  fractured  condition  of  the  beds  here  prohibits  an  estimate  of  the  strati- 
graohic  position  of  the  oil  sands  penetrated. 

"The  two  Tompkins  wells  and  the  Landrum  well  of  the  same  company  were 
drilled  in  Peachtree  Valley  and  are  said  to  have  reached  a  'hard  gray  sand'  without 
finding  more  than  a  trace  of  oil.  It  may  be  that  the  'gray  sand'  is  an  arkosic 
sand  derived  from  the  granite  and  is  similar  to  that  at  the  asphalt  quarry  west  of 
Lonoak,  but  the  writers  believe  that  it  is  more  probably  granite. 


80  CALIFORNIA   STATE    MINING   BUREAU. 

"The  Miller  well  of  the  Union  Oil  Co.,  near  the  west  edge  of  the  Peac-htroe  ranch 
along  the  road  from  Peaclitree  \'alley  to  Salinas  Valley  was  drilled  to  a  depth  between 
2500   and  liGOO  feet,   but  no  oil  was  found. 

"Economic   Possibilities. 

"Along  the  San  Andreas  fault  the  beds  are  broken  and  all  the  formations  are  so 
intermingled  in  small  irregular  masses  as  to  form  a  strueture  exceptionally  unfavor- 
able for  the  accumulation  and  retention  of  petroleum.  It  is  true  tliat  oil  contained 
>n  tlie  solid  rocks  in  tlie  immediate  vicinity  would  probably  work  its  way  into  tiie 
crushed  zone,  but  it  is  difficult  to  believe  that  it  would  be  held  there  in  quantity 
and  would  not  work  its  way  to  the  surface.  Thus,  although  seeps  of  oil  occur  along 
this  zone,  and  although  wells  such  as  Lonoak  well  No.  2  and  the  Salinas  well  have 
obtained  small  quantities  of  oil,  the  presence  of  oil  beneath  the  surface  in  suttic.ient 
amount  to  make  drilling  prcjHtable  seems  very  unlikelv.  Also,  the  experience  in 
other  California  fields  shows  that  oil  contained  in  rocks  so  badly  fractured  as  these 
IS  of  variable  character  and  that  much  of  it  is  of  heavv  gravitv.  Thus  the  oil 
found  in  the  Lonoak  and  Salinas  wells  is  probably  typical  of  the  oil  that  does  occur, 
despite  tlie  fact  that  small  quantities  of  light-gravitv  oil  have  been  found  in  shallow 
wells    on    Alvarez    Creek. 

"Of  the  3000  feet  or  more  of  Miocene  beds  which  are  infolded  in  the  Penchtree 
s>-ncline  near  Lonoak  tlie  lower  1000  feet  or  so  Is  largely  diatomaeeous  shale.  This 
shale  is  continuous  soulliward  but  seems  to  become  more  sandy  in  that  direction. 
That  the  beds  as.sociattd  with  the  shale  contain  some  oil  is  shown  bv  the  outcropping 
oil  sands  in  the  southeast  corner  of  the  Peachtree  ranch  and  by  the  results  obtained 
in  the  wells  near  tlu-  mouth  of  Lewis  Creek.  However,  the  writers  believe  it  doubtful 
that  oil  has  accumulated  here  in  any  considerable  amount.  Tlie  syncline  is  struc- 
turally isolated,  being  bounded  sharply  on  tlie  east  by  the  San  Andreas  fault  zone 
and  on  the  southwest  by  .the  granite  and  probablv  by  a  fault  extending  along 
Peachtree  Valley.  Thus  it  seems  improbable  that  oil  could  have  collected  in  this 
basin  from  the  rocks  underlying  any  very  extensive  area.  Any  oil  which  might 
have  been  formed  in  the  beds  beneath  Salinas  V'alley  would  probably  not  travel 
eastward  beyond  the  area  west  of  Peachtree  Valley,  in  which  the  Tertiary  beds  are 
wrinkled  irregularly.  Moreover,  except  in  a  small  area  near  the  mouth  of  Lewis 
Creek,  wliere  the  beds  are  slightly  domed,  the  general  synclinal  structure  is  not 
favorable  for  the  collection  of  petroleum.  Kven  tlie  doming  cited  is  really  so  slight 
and  lies  so  close  to  the  badly  fractured  San  Andreas  fault  zone  that  it  is  improbable 
that  oil  has  collectetl  in  it.  The  wells  which  have  been  drilled  here  have  pretty 
thoroughly  tested  the  area,  and  it  is  believed  that  further  drilling,  even  along  the 
small   fold   mentioned  above,   will   fail   to   disclose  any   extensive  accumulations  of  oil. 

"The  low  foothills  between  the  Peachtree  and  Salinas  valleys  present  many  of  the 
features  exhibited  liy  the  large  productive  tields  in  California,  and  in  this  area  alone, 
of  all  the  region  studied,  does  there  appear  to  be  a  possibility  of  obtaining  oil.  The 
factors  supporting  the  theory  that  oil  may  have  accumulated  here  in  considerable 
amounts  may  be  listed  as  follows:  (1)  Some  oil  is  undoubtedly  present,  as  is  shown 
by  the  outcropping  oil  sand  at  the  asphalt  (luarry  near  Lonoak  and  at  the  south  end 
of  the  Peachtree  ranch;  {-)  Diatomaeeous  shale,  which  is  regarded  as  the  ultimate 
source  of  the  oil  in  this  part  of  the  state,  is  bedded  with,  overlain  by,  and  underlain 
by  porous  sandstone,  wliich,  although  mostly  of  rather  fine  grain,  would  serve  as  an 
excellent  reser\-oir  for  oil;  (3)  The  sandy  beds  .are  somewJiat  lenticular  and  are 
intercalated  with  clay  or  shale,  thus  probably  furnishing  lociil  reservoirs  of  porous 
material  more  or  less  completely  inclosed  in  impervious  wells;  (4)  The  beds  are 
tilted  slightly  and  irregularly,  locally  forming  small,  low  structural  domes;  (5)  To 
the  west  is  the  broad  synclinal  Salinas  Valley,  under  which  lies  part  at  least  of  the 
thick  mass  of  diatomaeeous  shale  that  outcrops  along  the  Santa  Lucia  Range  on  the 
west  side  of  the  valley.  Thus  there  is  an  area  of  considerable  size  from  which  oil 
might    have   risen   to  collect   in   the  slightly   folded  rocks. 

"Although  the  broader  features  of  the  stratigraphy  and  structure  appear  to  favor 
the  hypothesis  that  oil  has  accumulated  in  the  foothills  west  of  Peachtree  Valley, 
two  important  questions  remain  to  be  answered,  and  to  neither  of  them  does  the 
answer  seem  favorable,  so  far  as  may  be  judged  from  the  areal  geology.  Tliey  are 
(1)  whether  the  oil.  though  undoubtedly  present,  was  formed  in  tiuantities  in  any 
way  comparable  with  those  found  hi  the  southern  end  of  the  San  Joaquin  Valley  ; 
and  (2)  whether,  if  any  considerable  (luantity  of  oil  was  formed  beneath  the 
valley,  it  would  have  collected  in  the  beds  in  the  foothills  on  the  east  side  in 
reservoirs  of  sufficient  size  to  be  commercially  valuable. 

"It  seems  probable  that  the  first  question  must  receive  a  negative  answer.  Seeps 
of  oil  and  dry  oil  sands  occur  not  only  in  the  region  described  but  also  to  the  south- 
east, in  the  Parkfield  region,  and  at  intervals  for  several  miles  on  the  west  side  of 
the  valley.  In  other  words,  the  outcrop  of  the  Tertiary  rocks  on  botli  sides  of  the 
basin  show  evidence  of  petroleum,  and  it  is  reasonable  to  suppose  that  the  beds  in 
the  center  of  the  basin,  now  covered  by  alluvium,  also  contain  or  at  one  time 
contained  it.  The  basin  occupied  by  sedimentary  rocks  here  is,  however,  of  much 
smaller  area  than  that  at  the  southern  end  of  the  San  Joaquin  Valley;  the 
diatomaeeous  shale  in  it  is  far  thinner  than  that  in  the  Temblor  Range  and  along 
the  east  side  of  the  Salinas  Valley,  is  somewhat  irregularly  developed,  owing,  in  part, 
to  Its  having  been  laid  down  upon  a  very  irregular  surface  of  granite  and  probably 
also  in  part  to  the  fact  that  it  is  replaced  in  some  areas  by  sandy  beds.  This 
irregularity  is  well  shown  along  the  San  Lorenzo  (^reek.  Near  Lonoak  the  lower  1000 
feet  or  so  of  the  later  Miocene  is  fairly  pure  diatomaeeous  shale,  but  less  than  2 
miles    downstream    sand    and    sandy    clay,    in    lithologic    character    precisely    like    the 


PETROLEUM   RESOURCES  OF   CALIFORNIA.  81 

beds  overlying  the  diatomaLeous  shale  near  Lonoak,  rest  directly  upon  the  granite. 
Also,  near  the  small  granite  exposures  some  4  miles  soutliwest  of  Ix)noak  the 
sedimentary  beds  are  entirely  sand  and  sandy  clay.  Tlui.'?,  if  the  diatomaceous  shale 
is  regarded  as  the  ultimate  source  of  the  oil  it  is  unreasonable  to  suppose  that  so 
great  nuantities  of  oil  were  formed  here  as  were  formed  in  tlie  southern  end  of  thc^ 
San   Joaquin   Valley. 

"Tlie  oil  seeps  in  the  region  studied  are  very  closely  associated  with  tlie 
diatomaceous  shale,  and  practically  none  is  known  in  an  area  in  which  the  shale 
has  not  considerable  development.  It  is  not  unreasonabla  to  suppose  that  beneath 
the  alluvial  filling  in  Salinas  Valley  the  diatomaceous  shale  has  as  irregular  a 
development  as  it  has  where  e.^posed  in  the  area  studied.  If  such  is  the  case,  unless 
there  is  some  special  cause  for  its  further  migration,  any  oil  which  may  have 
originated  in  tlie  sliale  would  probably  not  move  farther  than  the  sandy  beds 
interstratified  with  or  immediately  adjacent  to  the  shale.  Thus  the  tendency  would 
be  for  the  formation  of  a  number  of  small  local  concentrations. 

'•So  lar  as  the  effect  of  the  structure  upon  a  possible  accumulation  of  oil  is 
concerned,  the  most  notable  feature  in  tlie  foothills  between  Peachtree  and  Salinas 
valleys  is  the  lack  of  any  well-defined  fold  at  all  comparable  with  those  which,  soutli 
of  Coalinga,  border  tlie  San  Joaquin  Valley  on  the  west  and  along  which  lie  the 
productive  oil  tields.  Instead  of  being  strongly  folded  the  Tertiary  beds  along  the 
east  side  of  Salinas  Valley  are  but  sliglitly  tilled,  in  mueli  of  the  area  less  tlian  :i°. 
The  importance  of  this  difference  in  structure  can  hardly  be  overestimated  in 
considering   the  possibility   oi   oil   having  accumulated  in   considerable  quantity. 

"Along  the  edge  of  Salinas  Valley  the  dip  is  in  general  southwest,  but  near  the 
border  of  the  area  mapped  it  is  northeast.  The  cliange  does  not  take  place  along 
a  line,  but  rather  along  an  ill-dehned  belt  several  miles  in  width,  or  it  perhaps  may 
b^st  be  described  as  being  marked  by  a  number  of  short  irregular  domes  of  which 
three  appear  in  the  area  mapi)ed.  One  occurs  near  tlie  asphalt  quarry  west  of 
Lonoak,  where  the  later  Miocene  beds  dip  2°  to  7°  away  from  the  granite.  The 
second  occurs  west  of  the  Peachtree  ranch,  "vyhere  a  line  trending  northwest-southeast 
thiough  Sees.  IG  and  22,  T.  20  S.,  R.  10'  K.,  separates  the  beds  that  dip  about  2^" 
SW.  from  those  that  dip  approximately  as  much  northeast.  The  third  occurs  just 
northwest  of  tlie  isolated  outcroii  of  gianite  some  4  miles  southwest  of  Lonuak. 
These  uplifts  are  so  gentle  that  their  axes  cannot  well  be  designated  by  a  definite 
line,  but  their  position  is  indicated  by  tlie  dips  given  on  the  map. 

"In  San  Joaquin  Valley  the  sandy  beds  along  the  anticlines  have  served  as 
reservoirs  for  oil  tliat  is  believed  to  have  once  been  contained  in  beds  tliat  extended 
over  large  areas.  Much  of  the  oil  probably  originated  beneath  San  Joaquin  Valley, 
worked  its  way  up  the  rise,  and  aL-cumulated  in  the  upper  part  of  the  folds.  On 
the  east  side  of  Salinas  Valley,  however,  no  such  folds  dominate  the  structure  and 
there  appears  to  be  no  reason  why  oil  that  may  occur  disseminated  through  the 
rocks  over  a  wide  area  sliould  accumulate  in  considerable  amounts  in  a  single  area. 
On  the  contrary,  oil  which  may  have  originated  beneath  the  valley  would  probably 
tend  to  remain  in  the  upper  parts  of  the  numerous  low,  faint  domes  or  wrinkles. 
Moreover,  the  diatomaceous  shale  is  much  thinner  along  Salinas  Valley  than  It  is 
along  the  w^estern  border  of  San  Joaquin  Valley;  hence  it  is  even  more  necessary 
in  Salinas  than  in  San  Joaquin  Valley  that  a  structural  feature  which  favors  the 
accumulation  of  oil  should  have  tributary  to  it  a  large  area  from  wliich  oil  may  be 
drained. 

"In  conclusion  it  may  be  said  that  the  irregular  structure,  the  irregular  distribution 
of  the  diatomaceous  shale,  and  the  lenticular  character  of  the  sanuy  beds  all  seem 
to  indicate  not  that  oil  has  accumulated  in  any  considerable  quantity  in  few  lociilitie.s 
but  rather  that  it  has  accumulated  in  small  amounts  at  a  number  of  places  in  the 
upper  parts  of  low  folds  or  domes.  It  is  not  at  all  unlikely  that  wells  drilled  along 
the  axes  of  the  low  anticlinal  folds  that  lie  between  Salinas  River  and  Peachtree 
Valley  will  find  oil.  It  is  to  be  expected,  however,  that  the  area  that  may  prove 
productive  is  very  irregular  in  outline,  and  that  the  amount  of  oil  in  the  producing 
wells  will  be  small.  Thus  for  many  years  to  come  the  cost  of  prospecting  this  region 
■with  the  drill  will  probably  be  much  greater  than  the  value  of  the  oil  that  may  be 
obtained. 

"So  far  no  well  has  adequately  tested  the  area  west  of  the  Peachtree  Valley.  The 
well  most  advantageously  placed  is  the  Miller  well  of  the  Union  Oil  Co.,  which  was 
drilled  near  the  southwest  side  of  the  Peachtree  ranch,  about  a  mile  east  of  the 
line  of  change  in  dip,  in  Sees.  22  and  16.  Although  the  test  would  have  been  more 
satisfactory  had  the  well  been  located  farther  west,  still  the  failure  to  obtain  oil  in 
it  goes  far  to  prove  that  any  oil  sands  which  may  occur  here  are  of  small  extent. 
Also,  the  outcrops  of  granite  some  4  miles  southwest  of  Lonoak  are  signittcant,  for 
although  there  is  here  a  slight  fold  or  dome  comparable  with  that  near  Lonoak,  yet 
the   beds,    unlike   the  Tertiary   sands  at  Lonoak,   show   not  the  slightest   trace  of  oil. 

"OUTLYING    DISTRICTS. 

"The  -following  brief  notes  regarding  the  geology  and  possible  occurrence  of  oil 
in  the  Topo  ranch,  which  lies  beyond  the  boundary  of  the  area  shown  on  the  map, 
in  the  upper  part  of  the  valley  of  San  Benito  River,  are  based  on  hurried  visits  made 
during  the  course  of  the  work. 

"Topo   Ranch. 

"The  Peachti'^e  syncline  continues  as  a  broad,  shallow  fold  norlihwestward 
beyond  the  area  shown  on  the  map,  passing  through  the  Toi)0  ranch.  On  the  east  the 
syncline  is  terminated  bv  the  San  Andreas  fault  zone  and  on  the  west  by  the  granite 
which   here  appears   at   the   surface   in   the   Gabilan   Range.     Along   the   west   side   of 

G— 13  32 '2 


82  CALIFORNIA    STATE    MINING   BUREAU. 

tlie  syiiclinc  tlie  lower  part  of  the  Tirtiary  section  consists  of  chalky  white 
(liatomaceous  sliale  having  a  maxinnmi  thickness  of  not  more  than  1000  feet.  Upon 
the  shale  rest  a  few  hundred  feet  of  sandy  beds,  which  constitute  botli  tlie  Santa 
Mai-sarita  and  the  Tidare  formations.  The  beds  for  Tialf  a  mile  on  either  side  of 
the  axis  of  this  syncline  dip  at  angles  of  less  than  .5°  and  on  tlie  west  Hank  of  the 
ff)ld  at  angles  of  less  tlian  10°  as  far  as  the  granite  hills.  The  Matthews  asphalt 
ciuarry  (see  p.  147)  is  on  the  west  flank  of  this  syncline  at  the  contact  between  the 
granite  and  granite  and   overlying  Tertiary  beds. 

"Five  wells  have  been  drilled  by  the  Standard  Oil  Co.,  in  this  syncline  on  or  south 
of  the  Topo  ranch.  Some  of  them  were  drilled  tlirougli  th"  Tertiary  beds  to  the 
underlying  granite,  but  none  found  more  than  a  trace  of  oil  (jr  gas.  Their  names 
and  location  are  given  below : 

Dunne  No.  1,  Topo  ranch,  west  of  Dunne  ranch  liouse. 

Dunne  No.   2,  Topo  ranch. 

Blown  No.   1,  Sec.    15,   T.   17   S.,  R.   S   E. 

Stone  No.   1.  Sec.   27,  T.   17   S.,  R.   8  E. 

Leonard  No.   1,  Sec.   28,  T.   17  S.,  R.   S  E. 

"The  Leonard  well,  drilled  about  one-third  of  a  mile  east  of  the  Matthews  asphalt 
f|uarry,  started  in  tlie  diatomaceous  sliale  and  strucic  lieavy  oil  and  tar  not  far 
above  the  granite. 

"This  synclinal  basin  in  and  north  of  the  Topo  ranch  presents  few  features  which 
would  make  it  appear  probable  that  oil  lias  collected  in  it  in  considerable  quantity. 
It  is  isolated,  being  bounded  sharply  on  the  northeast  by  the  San  Andreas  fault 
zone  and  on  the  west  by  the  granite  of  the  Gabilan  Range,  and  is  tluis  almost  cut 
off  from  the  Tertiary  rocks  in  Salinas  Valley.  These  conditions  make  it  difficult 
to  believe  that  the  syncline  has  acted  as  a  catchment  basin  for  oil  drawn  from  great 
stretches  of  rocks  in  the  svirrounding  territory.  Moreover,  the  synclinal  sti'ucture 
is  not  especially  favorable  to  concentration  of  oil,  as  any  oil  that  did  exist  in  tliis 
rock  would  be  forced  up  the  Vise  and  would  appear  at  the  surface,  as  it  has  at  the 
Matthews  asphalt  ciuarry.  Finally,  the  wells  that  have  already  been  drilled  have 
pretty  thoroughly  tested  the  area. 

"San   Benito  River  Valley. 

"East  of  San  Benito  River,  near  the  southwest  corner  of  T.  17  S.,  R.  10  E.,  later 
Miocene  beds,  approximately  the  eciuiva'ent  of  the  Etchegoin  formation  of  the 
Coalinga  region,  dip  rather  regularly  20°-30''SW.  About  a  mile  northeast  of  the 
area  mapped  these  Vaeds  are  broken  by  a  fault  which  is  approximately  parallel  to 
the  San  Andreas  fault.  A  short  distance  nortlieast  of  tliis  fault  Cretaceous  Eocene  (?), 
and  F'ranclsean  (Jurassic?)  locks  appear.  Tlie  upper  part  of  the  Miocene  beds  is 
mainly  massive  arkosic  sandstone  filled  with  marine  fossils.  Beneath  these  beds  are 
alternating  beds  of  reddish  and  greenish  clay  and  gravel,  much  like  the  beds  that 
appear  along  the  axis  of  the  Vallecitos  syncline,  about  10  miles  away  on  the  opposite 
side  of  the  Diablo  Range,   and  presumably  of  upper  Miocene   age. 

"There  seems  to  be  no  reasonable  chance  of  obtaining  oil  in  this  part  of  the  San 
Benito  River  Valley.  So  far  as  known  no  seeps  of  petroleum  occur  here,  although 
the  rocks  are  broken  and  are  in  places  much  shattered  by  faults,  so  that  oil  certainly 
would  liave  had  abundant  opportunity  to  reach  the  surface  if  it  ever  liad  been 
present.  Also,  so  far  as  known,  no  masses  of  sedimentary  rocks  that  contain  any 
considerable  amounts  of  organic  material,  such  as  diatomaceous  or  carbonaceous 
shale,  occur  in  this  region.  Finally,  the  structure  is  not  especially  favorable  to  the 
accumulation  of  oil. 

"It  has  been  said  that  the  value  of  this  region  as  oil-producing  territorv  is  shown 
by  the  fact  that  it  lies  midway  between  Bitterwater  Valley  and  The  Vallecitos,  in 
both  of  which  seeps  of  oil  occur.  This  can  hardly  be  considered  a  valid  argument,  as 
the  .area  is  separated  from  the  Bitterwater  region  by  the  San  Andreas  fault  .and 
from  The  Vallecitos  by  a  great  mass  of  Cretaceous  and  Franciscan  (Jurassic?)  rocks, 
which  lie   stratigraphically  below   the  oil-bearing  rocks. 

"The  McMurtry-Hoeppner  well,  near  the  west  line  of  Sec.  32,  T.  17  S.,  R.  10  E.. 
is  on  James  Creek,  a  tributary  of  San  Benito  River  from  the  northeast.  The  well 
starts  in  the  fossiliferous  late  Miocene  beds  and,  when  visited  in  November,  1913, 
had  been  drilled  to  a  depth  of  14  62  feet,  and  had  apparently  reached  the  clay  and 
gravel  that  form  the  lower  part  of  the  upper  Miocene.  No  trace  of  oil  had  been 
obtained." 

Monterey  County. 

Monterey  County,  lying  in  the  central  coast  region  of  the  state,  bor- 
ders the  l^acific  for  a  distance  of  about  85  miles  and  stretches  back  into 
the  Coast  Ranges  witli  an  average  width  of  about  45  miles. 

The  principal  topographic  features  consist  of  the  Santa  Lut-ia  Range 
which  borders  the  coast  from  IMonterey  Bay  south  into  San  Luis  Obispo 
County,  reaching  elevations  of  from  3000  to  6000  feet ;  the  Salinas 
Valley,  which  drains  the  central  portion  of  the  county  for  its  entire 
length;  the  Cavilan  Range  which  boi'dcrs  the  Salinas  Valley  on  the 


PETROLEUM    RRSOURCES   OP    CALIFORNIA.  83 

east,  from  the  Pa.jaro  Kivcr  to  a  point  near  Kinj;  City.  South  of  Kiug 
City  the  ea.st  siiK'  of  tlie  Salinas  VaHcy  is  t-oniposed  of  low  rolling'  hills, 
which  gradually  rise  to  the  Temblor  Kange,  along  the  eastern  border  of 
the  county. 

The  county  will  ])e  divided  into  the  following  areas  and  the  oil  possi- 
bilities of  each  discussed:  (1)  ^louth  of  the  Salinas  Valley  and  the 
district  bordering  on  the  Bay  of  IMonterey.  (2)  Area  of  the  Santa  Lucia 
^Mountains.  (3)  Area  of  the  CJavilan  Mountains.  (4)  Salinas  Valley 
from  Salinas  to  Greenfield.  (5)  San  Antonio  Hills.  (6)  Salinas  Val- 
ley from  Greenfield  south  to  the  county  line.  (7)  Area  east  of  the 
Salinas  Valley  from  King  City  south  to  the  county  line. 

Mouth  of  the  SaHnas  Valley  and  District  Bordering  on  the  Bay  of  Monterey. 

This  region  may  be  considered  as  a  coastal  plain,  consisting  of  low 
rolling  hills  and  marsh  land  and  it  is  continuous  with  a  similar  area  in 
the  vicinity  of  Watsonville,  Santa  Cruz  County   (Chapter  VII). 

The  surface  fornuitions  consist  of  soft,  incoherent  sands  and  clays,  of 
a  yellow-brown  color,  probably  of  Quaternary  age.  There  is  no  definite 
evidence  as  to  what  underlies  these  beds,  but  it  is  probable  that  the 
Vaqueros  sandstone  and  diatomaceous  shale  of  the  ]\Ionterey  are  present 
beneath  a  portion  of  the  area.  Evidence  as  to  this  may  be  found  in 
examining  the  edges  of  the  district  and  noting  what  formations  appar- 
ently dip  under  it.  On  the  south  edge  in  the  vicinity  of  Del  Monte  and 
Seaside  the  ^Monterey  shale  which  forms  the  foothills  of  the  Santa  Lucia 
Range  is  dipping  to  the  northeast  and  apparently  disappears  beneath 
the  Quaternary  sands  just  southeast  of  Seaside.  From  this  point  east 
to  Salinas,  the  Quaternary  is  resting  against  sands  and  shales  of  the 
^Monterey  Series.  Along  the  east  edge  from  a  point  due  east  of  Salinas 
to  a  point  about  three  miles  southeast  of  Dumbarton,  the  Quaternary 
rests  directly  on  the  crystalline  rocks  of  the  Gavilan  Range.  This 
contact  may  be  seen  near  the  Lagunita  School,  along  the  State  Highway, 
from  Salinas  to  San  Juan.  From  the  vicinity  of  Dumbarton  north  to 
Aromas  on  the  Pajaro  River,  the  Quaternary  is  resting  against  a  massive 
medium  to  fine-grained  yellow  sandstone,  which  weathers  into  large, 
bold  outcrops.  The  dip  is  a])out  45°  to  the  southwest  and  thickness 
about  5000  feet.  Four  miles  due  east  of  Dumbarton  the  bottom  of  the 
formation  may  be  seen  resting  on  the  granite.  The  age  is  not  definitely 
known,  but  from  the  lithology  and  its  relationship  to  the  granite,  it 
can  probably  be  correlated  with  the  Vaqueros  sandstone  of  the  Santa 
Lucia  Range. 

AVhile  the  area  contains  no  evidence  of  petroleum,  it  has  certain  possi- 
bilities, similar  to  those  of  the  area  around  Watsonville.  These  pos- 
sibilities are  that  the  sands  and  diatomaceous  shales  of  the  Monterey 
Series  may  underlie  the  area  and  be  folded  into  favorable  structure 
hidden  beneath  the  Quaternary  sand.  The  area  is  therefore  worthy  of 
being  mapped  in  detail  to  discover  if  such  conditions  actually  exist. 

Area  of  the  Santa  Lucia  Mountains. 

This  district  occupies  that  portion  of  the  county  lying  south  of  Mon- 
terey and  west  of  the  Salinas  River.  The  San  Antonio  Hills,  a  detached 
range  of  the  Santa  Lucia  Mountains  lying  between  the  San  Antonio 
River  and  the  Salinas  Valley,  will  be  discussed  separately.  The  major 
portion  of  this  area  is  covered  by  crystalline  and  metamorphic  rocks. 


84  CALIFORNIA    STATE    MINING   BUREAU. 


ni 


These  may  be  divided  iuto  two  series.  The  older,  kiiuwii  as  the  Santa 
Lucia  Series  of  Paleozioc  age,  and  tlie  yomiger  series  Ijelonging  to  the 
Franciscan  formation  (Jurassic).  The  Santa  Lucia  Series  is  found  in 
the  north,  nortlieastern  and  western  portions  of  the  ai"ea  and  consists  of 
massive  limestones,  marbles,  schists,  granites  and  gneisses.  The  Fran- 
ciscan is  found  overlying  the  Santa  Lucia  in  isolated  patches  along  the 
coast  and  in  a  rather  broad  area  south  and  west  of  the  Nacimiento  River. 
It  consists  of  beds  of  altered  sandstone  slates  and  intrusive  serpentine. 
Tiie  area  occupied  by  these  two  series  may  be  considered  as  impossible 
for  oil. 

The  areas  occupied  by  sedimentary  rocks  and  which  could  possibly 
contain  oil  will  be  noted  below. 

The  first  of  these  areas  lies  along  the  valley  of  the  Carmel  River  and 
Tularcitos  Creek  and  the  low  foothills  between  ^Monterey  and  Salinas. 
The  formations  exposed  consist  mainly  of  diatomaceous  shales  of  the 
IMonterey  Series.  These  shales  vary  from  the  soft  chalky  form  to  the 
rather  hard  brittle  variety.  From  the  junction  of  the  Carmel  River 
with  Tularcitos  Creek,  _  southeast  to  Jamesburg,  the  shales  occupy  a 
narrow  trough  about  ten  miles  Avide,  between  the  main  range  of  the 
Santa  Lucia  ^Mountains  on  the  southwest  and  the  Soledad  HilLs  on  the 
northeast.  On  both  edges  of  the  trough  the  shales  rest  on  the  eroded 
surface  of  the  Santa  Lucia  Series.  From  Jamesburg  southeast  the 
Monterey  area  thins  to  about  two  miles  in  width  and  crosses  a  low'  divide 
in  the  vicinity  of  Sees.  35  and  36,  T.  18  S..  R.  4  E.,  joining  a  body  of  sedi- 
mentary rocks  along  the  Arroyo  Seco  on  the  east  slope  of  the  range. 

Along  the  Carmel  Valley  proper,  west  from  its  junction  with  Tular- 
citos Creek,  the  base  of  the  Monterey  is  resting  on  the  Santa  Lucia  Series 
along  the  south  side  of  the  valley.  The  general  structure  is  that  of  a 
monocline,  dipping  about  20°  to  the  northeast.  On  the  west  this  mono- 
cline rests  against  crystalline  rocks  along  Carmel  Bay  and  the  granite 
areas  west  of  the  town  of  ^Monterey.  On  the  east  it  is  prevented  from 
dipping  into  the  Salinas  Valley  by  the  granite  of  the  Soledad  Hills.  On 
the  north  it  dips  under  the  Quaternary  of  the  mouth  of  the  Salinas 
Valley,  along  the  edge  of  the  foothills  that  run  from  Monterey  to  Salinas. 
This  contact  is  described  in  the  previous  article  on  the  ''Mouth  of  the 
Salinas  Valley."  It  is  possible  that  in  the  vicinity  of  Toro  Creek  the 
Moutere}"  may  be  overlaid  by  sands  and  shales  of  the  upper  Miocene  and 
Pliocene  which  in  turn  dip  under  the  Quaternary  sands  of  the  valley. 
Along  the  north  and  south  sides  of  Carmelo  Bay  are  small  patr-hes  of 
coarse  sands  and  conglomerate,  probably  of  Eocene  age.  In  ^lalpaso 
Creek  about  two  miles  south  of  the  bay,  similar  beds  containing  coal 
occur.     The  total  thickness  of  this  Eocene  is  about  500  feet. 

Save  for  an  occasional  speck  of  bitumen  in  the  shale  there  is  no 
indication  of  petroleum  in  this  area.  This,  together  with  the  lack  of 
favorable  structure  and  reservoir  formations,  make  the  district  rather 
improbable  for  the  accumulation  of  oil. 

The  second  area  of  sedimentary  rocks  occurs  on  the  east  slope  of  the 
Santa  Lucia  Range,  opposite  the  Salinas  Valley,  between  Greenfield  and 
King  Citv.  This  body  of  sediments  is  best  exposed  alone  the  Arroyo 
Seco,  Reliz  Creek  and  Vaquero  Creek.  It  continues  west  from  the  edge 
of  the  Salinas  Valley  about  twelve  miles  and  the  bottom  is  exposed, 
resting  on  the  crvstalline  rocks  about  three  miles  east  of  Tassajara  Hot 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  85 

Springs.  A  small  l)ody  of  it  continues  nortlnvost  and  crosses  the 
divide,  joininia:  the  ^Monterey  area  southeast  of  Jamesbur<?.  On  the 
south  it  connects  with  the  sediments  of  the  San  Antonio  Hills  and  the 
San  Antonio  Valley. 

The  formations  that  eompo.se  this  body  of  sediments  are  as  follows: 
A  body  of  coarse  white  and  yellow  sandstone  about  2000  feet  thick,  con- 
taining near  the  base  conglomerate  beds,  made  up  of  fragments  of  ^lon- 
terey  shale.  This  formation  lithologically  resembles  the  Santa  i\Iar- 
garita  of  the  Salinas  Valley  and  it  can  probably  be  correlated  Avith  that 
formation.  It  is  found  outcropping  on  the  south  side  of  the  Arroyo 
Seco  at  its  mouth  and  forms  the  low  hills  that  border  the  west  side  of 
the  Salinas  Valley  from,  the  Arroyo  Seco  to  King  City.  It  dips  about 
15°  to  the  northeast  and  disappears  beneath  the  alluvium  of  the  valley. 
The  base  of  the  formations  is  exposed  along  Reliz  Creek,  resting  uncon- 
formably  upon  the  eroded  surface  of  the  Monterey  shale.  Along  the 
north  bank  of  the  Arroyo  Seco  from  its  mouth  on  west  to  the  headwaters 
in  T.  19  S.,  R.  5  E.,  are  outcrops  of  diatomaceous  shale  of  the  IMonterey. 
It  is  also  found  on  the  south  side  of  the  arroyo  in  the  area  west  of  Reliz 
Creek  and  in  the  vicinity  of  Vaquero  Creek.  It  is  very  probable  that 
the  general  inclination  of  the  strata  is  to  the  northeast,  but  the  shales 
have  been  so  fractured  that  any  accurate  mapping  of  the  structure  is 
impossible.  As  many  as  seven  sharp  folds  may  be  seen  within  a  distancs 
of  one-half  mile. 

Seepages  of  black  asphaltic  oil  are  reported  as  being  quite  common 
in  the  shale,  particularly  in  the  vicinity  of  faults.  The  principal  seep- 
ages occur  as  follows :  On  the  north  bank  of  Paloma  Creek,  about  the 
center  of  Sec.  21,  T.  19  S.,  R.  5  E. ;  at  a  fork  in  Piney  Creek  near  the 
west  quarter-corner  of  Sec.  12,  T.  19  S.,  R.  4  E.  This  latter  seepage 
is  probably  at  the  contact  of  the  shale  and  the  granite.  In  Sec.  20.  T.  19 
S.,  R.  6  E.,  at  the  north  quarter-corner,  a  well  was  sunk  to  a  depth  of 
1-400  feet,  encountering  salt  water  and  gas.  Up  Reliz  Creek  several 
seepages  are  reported  and  .shallow  wells  are  said  to  have  encountered  oil 
to  the  amount  of  almost  a  barrel  per  day. 

Beneath  the  Monterey  shale  is  found  a  rather  coarse  white  and  yellow 
sandstone.  It  is  best  exposed  about  seven  miles  up  Vaquero  Creek  from 
its  junction  with  the  Arroyo  Seco.  Homer  Hamlin^  first  described  it  at 
this  locality,  giving  it  the  name  of  Vaquero  sandstone,  and  hence  this 
locality  lias  been  regarded  as  the  type-section  for  the  Vaqueros  forma- 
tions. The  sandstone  is  resting  on  the  western  edge  against  the  crystal- 
line rocks  of  the  Santa  Lucia  Series. 

This  district  cannot  be  regarded  as  favorable  for  the  production  of 
oil  in  commercial  quantities  at  the  present  time.  While  the  Monterey 
shale  contains  evidence  of  petroleum,  it  is  probable  that  the  gi  eater 
portion  of  whatever  oil  was  once  in  the  shale  has  run  out  and  been  lost 
by  reason  of  the  severe  cru.shing  and  erosion  tj  which  the  shale  has 
been  subjected.  As  there  are  apparently  no  sand  beds  in  the  portion 
of  the  jNIonterey  that  is  left,  any  oil  present  would  have  to  collect  in 
the  fractured  zones  of  the  shale  and  showings  of  oil  can  probably  be 
obtained  by  drilling  along  faults. 

'U.   S.  Geological  Survey.     Water  Supply  Paper  89.     By  Homer  Hamlin. 


86  CALIFORNIA    STATE   MINING   BUREAU. 

In  the  strip  of  Santa  ^Margarita  which  overlies  the  ^Nlontere^'  with 
marked  unconformity  east  of  Reliz  Creek  no  indications  of  petroleum  are 
found,  and  it  is  probable  that  the  Santa  Margarita  sands  were  laid  down 
on  the  eroded  surface  of  the  IMonterey  long  after  the  oil  content  of  the 
shale  had  escaped. 

The  third  area  of  sedimentaries  in  the  Santa  Lueia  Range  runs  from 
the  vicinity  of  ]\Iount  Piron  south  to  the  San  Luis  Obispo  County  line 
and  lies  between  the  San  Antonio  and  Xacimiento  rivers.  On  the  east 
it  adjoins  the  sedimentary  rocks  of  the  San  Antonio  Hills  and  on  the 
west  it  is  bounded  by  the  metamorphic  rocks  of  the  Franciscan  formation 
lying  west  of  the  Naciemento  River.  The  rocks  that  outcrop  in  this  area 
consist  mainly  of  Vacpieros  sandstone.  A  small  area  of  Monterey  is 
found  south  of  Pleyto,  and  sandstone  and  shale  of  the  Santa  ^Margarita 
formation  outcrops  aloug  the  San  Luis  Obispo  boundary  line.  The 
thickness  of  these  formations  is  not  very  great,  for  at  Bald  ^Mountain 
a  considera])le  area  of  Franciscan  is  exposed  and  in  Sec.  22,  T.  24  S., 
R.  9  E.,  there  is  an  outcrop  of  granite  surrounded  by  the  ^[(mterey 
and  Santa  INIargarita  fornuitions.  This  district  shows  no  indications 
of  petroleum.^ 

Area  of  the  Gavilan  Mountains. 

The  eastern  one-half  of  the  Gavilan  ^fountains  lie  in  San  Benito 
County  and  the  western  half  form  the  northeastern  boundary  of  !Mon- 
terey  County.  This  portion  of  the  range  borders  the  Salinas  Valley  from 
its  most  northerly  point,  south  as  far  as  ]\Ietz.  South  of  ^letz  and  Topo 
Creek,  the  range,  wliieh  has  been  a  rugged  mountain  chain  with  eleva- 
tions as  high  as  3381  feet,  gives  way  to  low  rolling  hills  of  sedimentary 
rocks.  This  latter  area  was  discussed  in  the  article  on  San  Benito 
County.  As  stated  before,  the  rocks  of  the  Gavilan  Range  belong  to 
the  Santa  Lucia  Series  of  Paleozoic  age  and  consist  of  highly  meta- 
morphosed marbles,  schists  and  gneisses,  together  with  masses  of  intru- 
sive granite.  This  series  of  rocks  is  frecpiently  referred  to  as  the 
Basement  Complex  of  the  Coast  Ranges,  as  it  forms  the  core,  and  is 
the  oldest  formation  exposed  in  these  ranges.  There  is  no  evidence 
that  the  Santa  Lucia  formation  contains  oil  and  the  charactei'  of  the 
rocks,  together  with  the  intense  deformation  they  have  suffered,  prac- 
tically make  it  an  impossibility  for  them  to  contain  oil. 

Area  of  the   Salinas  Valley   from   Salinas  to   Greenfield. 

The  Salinas  Valley  from  Salinas  to  Greenfield  occupies  a  flat  area  of 
about  six  miles  in  width  and  33  miles  in  length.  It  is  bounded  on  the 
west  by  the  Santa  Lucia  Range  and  on  the  east  by  the  Gavilan  Mountains. 
The  formations  exposed  on  the  valley  floor  consist  of  recent  alluvial 
deposits,  which  on  both  sides  of  the  valley  rest  against  the  crystalline 
rocks  of  the  Santa  Lucia  Series.  It  is  probable  that  the  structure  con- 
sists of  a  synclinal  trough  between  the  two  mountain  ranges,  with  the 
crystalline  rock  forming  the  syncline  and  the  recent  alluvial  deposits 
resting'  horizontallv  on  the  older  rocks.     The  western  side  of  the  valley 


•"The  soutliwfst  portinn  of  this  area  has  been  mapped  by  the  State  Mining  Bureau 
and  published  in  tlie  folio  tliat  accompanies  Bulletin  69,  "Petroleum  Industry  of 
California." 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  87 

is  characterized  by  larjje  alluvial  fans  running  out  of  the  steep  canyons 
of  the  Santa  Lucia  Ran^e  and  a  fault  of  considerable  magnitude  prob- 
ably parallels  the  west  side  of  the  Salinas  River. 

The  apparent  lack  of  any  sedimentary  deposits  other  than  the  recent 
alluvium  make  this  portion  of  the  valley  unfavorable  for  the  accumu- 
lation of  oil. 

The  Area  of  the  San  Antonio  Hills. 

The  San  Antonio  Hills  may  be  considered  as  a  detached  portion  of  the 
Santa  Lucia  Range,  lying  between  the  Salinas  Vallej'  and  the  San 
Antonio  Valley-.  Tlie  northern  limits  will  bo  fixed  as  terminating  on 
a  line  running  due  west  from  King  City.  On  the  south,  while  the  hills 
actually  terminate  at  the  bend  of  the  San  Antonio  River,  for  the  purpose 
of  this  report  that  portion  of  San  Luis  ()l)ispo  County  lying  between  the 
east  bends  of  the  San  Antonio  and  Xaciemcnto  Rivers  will  be  considered 
as  a  part  of  the  area  under  discussion. 

The  San  Antonio  1 1  ills  may  be  considered  as  a  fault  block  bordered 
by  well  defined  faults  on  two  sides  On  the  east  the  hills  are  separated 
from  the  Salinas  Valley  by  a  fault  that  runs  along  the  west  side  of  the 
valley  from  its  mouth  to  a  point  al)out  five  miles  south  o-f  San  Ardo. 
The  fault  on  the  west  side  begins  about  six  miles  north  of  Jolon,  in  Sec.  3, 
T.  22  S..  R.  7  E.,  and  runs  southeast  along  the  east  side  of  the  San 
Antonio  Vallev.  crossing  the  San  Antonio  River  and  the  San  Luis  Obispo 
boundary  line'in  the  SW.  i  of  See.  34,  T.  24  S.,  R.  10  E.  The  formations 
within  this  fault  block  consist  mainly  of  diatomaceous  shale  beds  of  the 
Monterey  Series  (called  by  the  United  States  Geological  Survey,  'Salinas 
Shale').  Owing  to  the  intense  crushings  and  foldings  which  the  shale 
has  undergone,  no  definite  statement  can  be  made  as  to  the  thickness  or 
structure.  In  three  areas  the  shale  is  overlaid  by  beds  of  incoherent 
sand,  gravel  and  clays  of  fresh-water  origin,  known  as  the  Paso  Robles 
formation  ( Pliocene).  These  areas  are  as  follows  :  In  the  Hames  Valley, 
about  four  miles  northea.st  of  Bradley,  the  Paso  Rol)les  beds  are  folded 
in  a  broad  synclinal  trough ;  at  the  ea.st  bend  of  the  San  Antonio  River, 
about  six  miles  southwest  of  Bradley,  the  Paso  Robles  is  present  along 
the  axis  of  a  small  syncline  and  along  the  fiank  of  tlie  corresponding 
anticline;  along  the  east  side  of  the  San  Antonio  Hills,  between  King 
City  and  a  point  three  miles  north  of  San  Ardo,  the  Paso  Robles  is  present 
in  a  monocline,  lying  on  the  Monterey  and  dipping  at  a  rather  high 
angle  to  the  east.  Several  seepages  of  petroleum  have  been  reported  as 
occurring  in  the  ^Monterey  shale  beds,  probably  along  fault  lines.  The 
most  notable  of  the  seepages  occur  in  what  is  known  as  the  Pleyto  Dis- 
trict. This  district  lies  about  six  miles  southwest  of  Bradley  in  the 
vicinity  of  the  eastward  bend  of  the  San  Antonio  River.  This  district 
has  been  mapped  and  reported  on,  both  by  the  State  ]\lining  Bureau^ 
and  the  United  States  Geological  Survey-. 

Following  is  a  portion  of  the  Geological  Survey  report  by  W.  A.  Eng- 
lish dealing  with  the  Plevto  District.     The  term  Salinas  shale  used  in 


'California  State  Mining  Bureau.      Bull.  69,   1914.      Pp.  435-436. 
=U.  S.  Geological  Survey.      Bull.   691-H.     By  Walter  A.  Knglisli. 


88  CALIFORNIA    STATE    MINING    BUREAU. 

INIr.  English's  report  is  synonymous  with  ^Monterey  shale,  as  used  in  this 
Bulletin : 

"Pleyto  Oil   District. 

"The  Pleyto  district  (see  Fig.  36)  lies  near  the  bend  in  San  .Antonio  River,  about 
.<:ix  miles  southwest  of  Bradley  and  eight  miles  southeast  of  Pleyto.  Attention  of 
oil  men  was  early  attracted  to  this  area  by  the  outcrops  of  asphalt  rock,  and  a 
number  of  wells  have  been  drilled,  but  they  did  not  encounter  enough  oil  to  justify 
pumping. 

"Structure. — The  anticline  that  crosses  the  SWJ  Sec.  36.  T.  24  S..  R.  10  E.. 
constitutes  a  structural  spur  extending  out  into  the  area  of  gently  dipping  beds  of 
the  Paso  Robles  formation,  very  much  like  the  productive  anticlines  in  San  .Joaquin 
Valley,  though  on  a  much  smaller  scale.  Owing  to  this  similiarity  it  has  been 
thought  that  oil  may  have  accumulated   in   this  anticline. 

"Indications  of  oil. — The  basal  150  feet  of  beds  of  the  Paso  Robles  formation 
along  the  contact  just  south  of  San  .Antonio  River  are  impregnated  with  asphalt. 
The  quality  of  the  asphalt  rock  is  variable,  the  best  being  confined  to  a  bed  of  fine 
sandstone  about  20  feet  thick.  An  open  cut  has  been  made  in  this  bed,  and  what 
probably  amounts  to  several  hundred  wagon  loads  of  asphalt  rock  has  been  removed 
for  local  use  in  road  making.  To  the  southeast  there  are  stringers  of  rich  asphalt 
rock  in  the  basal  Paso  Robles  beds  where  tliey  cross  the  Nacimento  River,  and 
small  pockets  of  sand  that  has  been  squeezed  into  the  underlying  Salinas  shale  are 
heavily  impregnated  with  asphalt.  The  Salinas  shale  adjacent  to  the  Paso  Robles 
is  hard  and  broken  into  angular  fragments,  between  which  a  tar  cementing  material 
is  locally  present.  The  tar  occurs  only  on  the  surfaces  of  the  shale  fragments  and 
seems  to  have  migrated  to  this  locality  from  elsewhere  in  the  shale. 

"Economic  possibilities. — The  Salinas  shale  is  the  probable  source  of  any  oil 
present  in  this  district,  and  the  most  likely  collecting  place  of  the  oil  would  be  in 
the  overlying  Paso  Robles  or  in  the  Santa  Margarita  sandy  beds  where  they  are 
present.  The  asphalt  along  the  outcrop  of  the  Paso  Robles  on  the  west  side  of  the 
syncline  furnishes  direct  evidence  of  the  presence  now  or  formerly  of  oil  in  the 
district.  Against  these  favorable  features  may  be  urged  the  following:  (1)  The 
bed  of  asphalt  rock  is  150  feet  thick  just  south  of  San  Antonio  River  but  thins  out 
to  a  few  feet  within  a  quarter  of  a  mile  in  each  direction,  and  there  is  no  aspha't  in 
Sec.  26  in  the  sandy  beds  on  the  flank  of  the  anticline.  The  accumulation  of  asphalt 
appears  to  be  due  to  fractures  in  the  shale  caused  by  movement  along  a  fault  that 
continues  eastward  from  Sec.  33,  where  it  forms  the  contact  between  the  Salinas 
shale  and  the  Vaqueros  formation.  These  fractures  apparently  allowed  a  ready 
migration  from  the  shale  into  the  overlying  Paso  Robles.  Thus  the  presence  of 
asphalt  here  is  apparently  not  due  to  the  anticlinal  structure  to  the  east  and  is  not 
very  good  evidence  of  a  concentration  of  oil  in  the  anticline.  (2)  The  four  wells 
that  tested  the  beds  overlying  the  shale  got  negative  results.  The  Metropolis  well, 
which  passed  through  the  Paso  Robles  into  the  imdeilying  shale  without  encountering 
eitlier  oil  or  tar  sand,  furnishes  the  best  test.  Two  shallow  wells  close  to  the  outcrop 
near  the  south  line  of  Sec.  35.  got  tar  sands  but  no  oil.  The  King  well  of  the  Bradley 
Oil  Company  is  said  not  to  have  reached  the  Salinas  shale  so  its  results  are  incon- 
clusive. The  Metropolis  well  went  far  toward  proving  the  absence  of  oil  in  this 
anticline.  However,  the  King  well  should  be  depended  to  reach  the  shale.  If,  after 
reaching  the  shale,  it  proves  a  failure  also,  more  drilling  in  the  field  would  seem 
Inadvisable,  though  a  well  a  quarter  to  half  a  mile  east  of  the  King  well  would  give 
the  most   conclusive  test  of  the  anticline. 

"Wells  drilled  for  oil. — The  wells  drilled  in  the  Pleyto  district  are  here  listed 
and  numbered  to  correspond  with  mmibers  on  the  geologic  map  (Fig.  36)  : 

"Well  No.  1,  in  Sec.  27,  drilled  by  the  Monterey  Oil  Co.  (?)  is  said  to  have  reached 
a  depth  of  1100  feet  and  struck  flowing  water. 

"Well  No.  2.  in  the  SEJ  Sec.  26.  drilled  by  the  Pleyto  Oil  Co.  and  successors,  is 
said  to  have  reached  a  depth  of  3300  feet,  getting  a  small  quantity  of  tarry  oil  near 
the  bottom.  It  is  in  the  Salinas  shale  for  at  least  the  tipper  3100  feet.  Drilling  was 
started  about   1000   and  finished   1912. 

"Well  No.  3,  the  Metropolis  well,  in  Sec.  35,  drilled  by  the  Hames  Valley  Oil  Co. 
in  1911-1913,  is  3100  feet  deep  and  obtained  only  a  small  quantity  of  heavy  oil.  The 
drill  entered  the  shale  at  a  depth  of  about  1000  feet  without  having  passed  through 
any   tar   sands. 

"Well  No.  4,  in  the  southwest  corner  of  Sec.  36,  drilled  by  the  Bradley  Oil  Co. 
(King  well),  is  said  to  have  reached  a  depth  of  not  more  than  SOO  to  900  feet.' 

"Well  No.  5  (location  approximate)  was  drilled  about  1900  by  the  White  Oaks 
Oil  Co.  Another  well,  drilled  by  the  Great  American  Oil  Co.  is  a  few  hundred  feet  to 
the  south.  Both  are  close  to  the  outcrop  and  are  said  to  have  penetrated  the  asphalt 
sands. 

"Well  No.  6,  the  Cavanaugh  well,  drilled  with  a  standard  rig,  is  said  to  have 
reached  a  depth  of  800  fet  in  the  Salinas  shale. 


'Since  the  above  was  written,  the  King  well  was  taken  over  by  the  Associated  Oil 
Co.  and  deepened  to  2035  feet,  when  it  was  abandoned.  Through  the  courtesy  of  the 
company  the  writer  has  been  furnished  with  the  log.  According  to  the  writer's 
interpretation,  the  drill  reached  the  Salinas  shale  at  1445  feet.  Seven  feet  of  tar  sand 
was  passed  through  at  a  depth  of  1320  to  1327  feet,  but  no  other  oil  or  tar  sands 
were  encountered. 


PETROLEUM   RESOURCES  OP   CALIFORNIA.  89 

"Well  No.  7.  the  other  Cavanaiigh  well,  drilled  with  a  portable  rig,  is  said  to  have 
reached  a  depth  of  2500  feet  without  getting  any  apprecial)le  fiuantity  of  oil.         ,* 

"The  Veratina  well,  on  the  south  bank  of  San  Antonio  River  about  a  .quarter  of 
a  mile  east  of  tlie  west  line  of  Sec.  3  5,  is  said  to  have  been  drilled  sliortly  after  1900 
and^to   have   encountered   considerable   salt  water   and   some   gas." 

The  general  geological  conditions  for  the  accumulation  of  oil  in  the 
San  Antonio  Hills  is  unfavorable.  A  more  detailed  statement  regarding 
these  conditions  is  given  in  the  following  article: 

The  Salinas  Valley  from  Greenfield  South  to  the  County  Line. 

The  geology  and  oil  resources  of  this  area  have  l)een  reported  on  in 
detail  both  by  the  State  ]^Iining  Bureau^  and  the  United  States  Geolog- 
ical Survey. - 

The  ]\Iining  Bureau's  report  covers  the  entire  portion  of  the  Salinas 
Valley  south  of  King  City,  and  the  Geological  Survey's  report  takes  in 
that  portion  of  the  valley  from  the  vicinity  of  San  Ardo  to  a  point  about 
Ihree  miles  south  of  San  ]\liguel  The-se  reports  contain  detailed  geolog- 
ical maps  of  the  district,  together  with  a  list  of  wells  drilled  in  the  area. 
The  general  geology  of  this  region  may  be  summed  up  as  follows:  The 
Tertiary  sedimentary  rocks  that  occupy  this  portion  of  the  Salinas  Valley 
lie  in  a  broad,  shallow  syncline  between  the  Diablo  Range  on  the  east 
and  the  Santa  Lucia  Range  on  the  west.  The  axis  of  the  syncline  approxi- 
mately parallels  the  center  of  the  valley.  Along  the  east  side  of  the 
valley,  the  east  limb  of  the  syncline  is  formed  by  beds  of  the  Santa  i\Iar- 
garita,  Etchegoin  and  Jacalitos  and  Paso  Robles  formations,  dipping  at 
about  4°-to  the  west.  These  beds  probably  flatten  out  beneath  the  allu- 
vium of  the  valley  floor  and  then  turn  and  clip  to  the  east  on  the  west 
side  of  the  valley.  From  King  City  south  to  a  point  about  three  miles 
south  of  San  Ardo,  this  -west  limb  of  the  syncline  is  sharply  faulted  and 
the  upper  Miocene  and  Pliocene  beds  rest  at  a  sharp  angle  against  the 
]\ronterey  shale  of  the  San  Antonio  ITills.  This  fault  contact  may  be 
plainly  seen  in  the  hills  west  of  San  Ardo,  the  Santa  ^NFargarita  resting  at 
an  angle  of  about  7(1^  to  the  east  against  the  iMonterey,  which  dips  to  the 
west.  This  fault  apparently  dies  out  about  six  miles  north  of  Bradley, 
and  the  upper  ^Miocene  and  Pliocene  beds  rest  with  their  normal  uncon- 
formitv  on  the  INIonterev  from  this  point  on  south.  Beginning  at  a 
point  about  four  miles  north  of  Bradley,  in  Sec.  23,  T.  23  S.,  R.^10  E., 
a  broad,  plunging  anticline  appears,  which  runs  southeast  through  the 
town  of  Bradley  and  gradually  dies  out  in  the  hills  about  three  miles 
east  of  San  iMiguel  This  fold  is  known  as  the  Bradley  anticliue.  The 
Paso  Robles  beds  are  exposed  on  the  surface  of  tlie  fold  and  well  logs 
indicate  that  the  IMonterey  is  present  beneath  the  Paso  Robles.  The 
Bradley  anticline  is  apparently  the  most  favorable  location  to  obtain  oil 
in  the  Salinas  Valley.  It  fulfills  at  least  three  conditions  necessary  for 
the  accumulation  of  petroleum — that  is  (1)  the  structure  is  favorable; 
(2)  beds  of  organic  shale  underlie  the  fold;  (3)  porous  reservoir  beds 
are  present  overlying  the  organic  shale.  Nevertheless,  with  all  these 
qualifications,  this  fold  has  to  date  failed  to  show  oil  in  commercial 
quantities.  It  is  the  opinion  of  the  writer  that  this  is  due  to  the  fact 
that  the  Monterey  shale  from  which  the  oil  would  have  to  come  was 

^California  State  Mining  Bureau.      Bull.   69.      Pp.  418-432.      By  C.  A.  Waring. 
^United  States  Geological  Survey.     Bull.  691-11.      Salinas  Vallcv-Parkfield  Area.     By 
W.  A.  English. 


90  CALIFORNIA    STATE   MINING   BUREAU. 

uplifted  and  eroded  with  the  loss  of  most  of  its  oil  content  previous  to 
the  time  at  which  the  upper  INFiocene  and  Pliocene  beds  were  laid  down. 
Hence  these  beds  show  no  oil,  and  the  ]\Ionterey  contains  only  small 
quantities  in  its  lower  portion.  This  ai>plies  in  general  to  those  areas  in 
IMonterey  and  San  Luis  Obispo  counties  where  the  ^Monterey  shale  and 
the  Paso  Robles  formation  are  exposed. 

The  following  wells  have  been  drilled,  or  are  drilling,  in  the  Bradley 
anticline :  A  well  in  Sec.  4,  T.  25  S.,  R.  12  E.,  is  said  to  have  been  drilled 
to  1340  feet,  getting  small  amounts  of  gas  but  no  oil.  This  well  was 
apparently  located  in  the  axis  of  the  Bradley  anticline.  Just  south  of 
the  town  of  Bradley  and  located  on  the  axis  of  the  fold,  the  Bradley- 
San  Miguel  Oil  Company  has  a  well  down  about  2000  feet.  Showings 
of  oil  and  ga§  have  been  reported. 

In  Sec.  32,  T.  24  S.,  R.  12  E.,  the  Shell  Company  of  California  has  a 
well  down  4200  feet.  This  well  is  located  approximately  on  the  axis  of 
the  fold  and  apparently  went  through  the  Pliocene  beds  at  1600  feet, 
logging  ]Monterey  shale  from  tbat  point  to  its  present  depth.  Several 
showings  of  oil  have  l)een  reported  in  the  ^Monterey,  but  nothing  of  com- 
mercial value  has  been  found  to  date. 

In  the  area  west  of  San  Ardo  along  the  fault  contact  between  the  IMon- 
terey and  Santa  Margarita,  there  are  several  seepages  of  oil.  Following 
is  a  portion  of  English's^  report  on  this  territory: 

'•Area   West  of  San  Ardo. 

"Geology. — Tlu/  San  Antonio  Hills,  along  the  west  side  of  Salinas  River,  consist 
entirely  of  the  Salinas  sliale,  except  for  a  belt  of  the  sandstone  and  shale  of  tlie  Santa 
Margarita  formation  about  a  lialf  mile  wide  close  to  the  edge  of  tlie  valley.  The 
Santa  Margaiita  beds  in  this  lielt  overlie  the  Salinas  shale  with  marked  imconformity. 
Tliey  dip  40°  to  60'  NE.,  in  marked  contrast  to  tlie  gently  dipping  beds  of  the  same 
age  on  the  east  side  of  the  river.  There  must  be  a  syncline  or  a  faulted  syncline  some- 
wliere  beneatli  tlie  valley  alluvium  and  terrace  formation,  but  there  is  no  surfai-e 
evidence  to  indicate  wliere  tlie  syncline  sliown  on  Plate  XXVII  really  lies  beneatli  the 
Quaternary  cover.  The  Santa  Margarita  is  here  markedly  unconformable  on  the 
Salinas  shale. 

"Evidence  of  oil. — In  Garrissere  Gulch,  west  of  San  Ardo,  tar  sands  in  the  Santa 
Margarita  extend  through  a  thickness  of  several  hundred  feet ;  farther  south,  in 
Sec.  19,  T.  TJ,  S.,  R.  10  E.,  the  lower  beds  of  the  Santa  Margarita  are  richly  impreg- 
nated with  oil  and  tar;  and  other  oil  sands  are  exposed  close  to  the  base  of  the 
sandstone  as  far  south  as  the  southern  limit  of  this  belt  of  Santa  Margarita  in  Sec.  Z'.i. 

"P>-onomic  possibilities. — Surface  evidence  indicates  that  the  oil  migrated  from 
the  underl>ing  shale  into  the  Santa  Margarita,  and  that  it  is  confined  to  the  west  side 
of  the  syncline  which  lies  somewhere  out  in  the  valley.  The  abundance  of  oil  sands 
at  the  surface  suggests  that  oil  might  be  obtained  by  wells  that  would  reach  the 
lower  part  of  the  Santa  Margarita  at  a  considerable  depth.  The  best  place  for  a 
test  is  opposite  the  best  outcropping  oil  sands,  which  occur  between  the  north  line 
of  Sec.  13,  T.  22  S.,  R.  9  E.,  and  the  south  line  of  Sec.  19,  T.  22  S.,  R.  10  E.  The 
well  should  be  far  enough  cast  of  the  outcrop  to  reach  the  base  of  the  Santa 
Margarita  at  a  depth  between  1000  and  1500  feet. 

"Wells  drilled  for  oil. — The  wells  drilled  in  this  area  are  described  below  in 
order  from  north  to  south.  They  were  all  drilled  some  time  ago,  and  the  information 
obtained   about   them   is   fragmentary. 

"The  Newell  well,  east  of  Sec.  12,  T.  22  S.,  R.  9  E.,  is  said  to  have  reached  a  depth 
of  1310  feet.  It  probably  entered  the  oil  sands  at  about  600  feet  and  continued  in 
them  to  the  bottom.  It  furnishes  a  fair  but  incomplete  test  of  this  area,  as  it 
should  have  been  drilled  to  the  underlying  shale,  which  is  here  probably  several 
hundred    feet    deeper. 

"The  Capl.  Barrett  well,  near  the  north  line  of  Sec.  19,  T.  22  S.,  R.  10  E..  is  said 
to  have  reached  a  depth  of  SOO  to  1000  feet.  It  is  located  too  close  to  the  basal 
contact  to  test  the  Santa  Margarita. 

"The  Tomboy  well,  about  1800  feet  southeast  of  the  Barrett  well,  is  said  to  have 
reached  about  the  same  depth.  It  probably  entered  the  Salinas  shale  at  from  500 
to  600  feet  and  proves  that  at  that  depth  the  overlying  Santa  Margarita  does  not 
contain  oil. 


'U.  S.  Geological  Survey.      Hull.  i;9l-H.      By  W.  A.  English. 


PETKOLELM    RESOURCES   OF    CALIFORNIA.  91 

"The  Doluny  well,  in  the  southwest  corner  of  Sec.  20,  T.  22  S.,  R.  10  E.,  is 
practically  on  the  basal  contact  of  the  Santa  Marsarita.     Its  denth  was  not  learned. 

"The  well  of  the  Norman  Oil  Co..  in  the  northeastern  part  of  Sec.  4,  T.  23  S.. 
R.  l(t  E.,  starts  down  in  the  Salinas  shale  on  the  north  Hank  of  a  well-marked 
anticline.     Its  deptli  and  history  were  not  learned." 

Area  East  of  the  Salinas  Valley  from  King  City  South  to  the  County  Line. 

This  district  may  be  considered  as  enibracintr  the  territory  that  lies 
between  the  Kings  t'ounty  line  and  the  headwaters  of  the  streams  that 
drain  into  the  Salinas  Valley,  with  a  Icnfrth  north  and  south  from  Lonoak 
to  the  Chalome  Ranch.  It  is  characterized  l)y  a  number  of  narrow  north 
and  south  valleys,  chief  of  which  are  Lewis  Creek,  Peachtree  Valley  and 
Priest  Valley  in  the  northern  portion  and  Chalome  Creek  and  the  Park- 
field  area  in  the  southern  pnrtinu.  The  district  has  been  mapped  in 
detail  both  by  the  Gcolo.uical  Survey'  and  the  State  .Alinin^i;  Bureau-. 

The  general  geology  of  the  region  may  be  summed  up  as  follows :  Along 
the  ridge  that  divides  this  area  from  the  Salinas  Valley  the  formations 
consist  of  white  sandstone  and  diatomaceous  shale  of  the  Santa  ]Mar- 
garita.  overlaid  in  i)laces  by  the  sands  and  gravels  of  the  Pliocene.  The 
general  dip  is  about  10°  to  the  west.  The  Santa  ^Margarita  is  apparently 
resting  on  the  eroded  surface  of  the  granite.  Along  the  ea.st  side  of  the 
Peachtree  Valley  there  is  a  syncline  in  the  upper  ^Miocene  formations. 
Running  along  headwaters  of  Big  Sandy  Creek  and  Vineyard  Canyon 
and  thence  southeast  into  the  Chalome  Ilills  is  the  axis  of  an  anticline, 
partly  in  the  Santa  ^largarita  and  partly  in  the  Pliocene. 

The  San  Andreas  fault,  which  is  the  dominant  feature  of  this  area, 
runs  south  down  Lewis  Creek  and  then  across  a  divide  into  Charley 
Valley  and  thence  across  another  divide  into  Chalome  Creek  and  con- 
tinues south  down  the  latter,  passing  just  east  of  Parkfield. 

The  fault  zone  averages  about  three  miles  in  widtli  and  the  formations 
expo.sed  along  the  rift  consist  of  the  basement  conii)lcx,  the  Franciscan, 
the  Chico,  the  Vaqueros  and  the  Santa  ^Margarita.  All  the  beds  have 
been  sharply  tilted  and  crushed  and  the  area  occupied  by  any  one  forma- 
tion is  relatively  small.  In  the  area  east  of  the  fault  the  upper  ^Miocene 
formations  are  fountl  lying  on  the  Chico  aiul  the  Franciscan. 

Indications  of  oil  are_found  along  the  Peachtree  Valley  and  in  the 
vicinity  of  the  San  Andreas  fault,  particularly  in  the  Parkfield  area. 
The  oil  apparently  originated  in  the  diatomaceous  shales  of  the  Santa 
]\Iargarita  and  has  collected  at  the  contact  of  this  formation  with  the 
underlying  granites,  or  where  the  shales  have  been  brought  in  contact, 
by  faulting,  with  the  Pliocene  sands.  Sec.  E-F,  Fig.  6,  shows  the  general 
structure  in  the  northern  portion  of  this  region. 

The  unfavorable  structure  and  the  lack  of  any  great  amount  of  diato- 
maceous .shale,  make  the  region  unfavorable  for  the  accumulation  of 
petroleum  in  any  large  quantities. 

'U.  S.  Geological  Survey.  Bull.  5S1-D.  Geology  and  Oil  Prospects  in  the  Waltham, 
Priest,  Bitterwater  and  Peachtree  Valleys,  1914.      By  R.  W.  Pack  and  W.  A.   English. 

U.  S.  Geological  Survey.  Bull.  691-H.  Geology  and  Oil  Prospects  of  the  Salinas 
Valley- Parkfield  Area,  1918.     By  W.  A.  English. 

-California  State  Mining  Bureau.      Bull.  69.     Petroleum  Industry  of  California,  1914. 


92  CALIFORNIA   STATE    MINING   BUREAU. 

In  the  article  on  San  Benito  County,  page  78,  a  portion  of  Pack  and 
English's^  report  on  the  Peachtree  area  is  given.  Below  is  a  portion  of 
the  same  report  dealing  with  the  Parkfield  area : 

"Parkfield    District. 

"The  Parkfield  district  (Fig.  35,  PI.  XXVIII)  li(s  In  .in  elevated  part  of  the 
Diablo  Ran^e  about  2S  miles  from  Coalinsa,  in  San  Joaquin  Valley,  and  22  miles 
from  San  Miguel,  in  the  Salinas  Valley,  the  two  nearest  railroad  points.  Despite 
the  DOor  transDortation  facilities  the  presence  of  numerou.s  oil  seepages  hero  has 
led  to  the  drilling  of  a  number  of  wildcat  wells,  thougli  without  any  distinctly 
,  favorable  results.  Nevertheless,  there  are  many  people  who  still  believe  that  the 
district  will  ultimately   prove  productive. 

"Stratigraphy  and  structure. — Thou.gh  most  of  the  formations  common  to  the 
Coast  Range  crop  out  within  this  area,  the  onl.v  one  present  in  which  oil  is  likely 
to  have  originated  is  tlie  Santa  Margarita  (.?)  form.aiion,  which  is  exposed  on  the 
-southwest  flank  of  the  syncline  east  of  Parkfield.  Oil  is,  therefore,  to  be  looked  for 
only  in  beds  adjacent  to  this  formation  and  particularly  those  overlying  it.  in  areas 
of  favorable  structure.  The  beds  throughout  tlic  Parkfield  district  dip  steeply, 
and  the  structure  is  complicated.  Toward  the  north,  where  the  Parkfield  syncline 
approaches  the  San  Andreas  fault,  beds  of  widely  different  ages  have  been  brought 
close  together  by  the  extensive  faulting.  East  of  Parkfield,  the  syncline  is  less 
faulted  but  presents  a  remarkable  disparity  in  the  succession  of  formations  out- 
cropping on  tlie  two  sides  of  the  axis.  It  may  be  seen  from  Plate  XX\'11I  that  the 
Vaqueros  formation  and  th-.^  Santa  M.argarita  (?)  formation,  which  are  well  developed 
on  tlie  soutliwest  side  of  the  .fold,  are  aVjsent  on  the  northeast  side,  along  the  flank 
of  Table  Mountain.  The  absence  of  tliese  beds  is  accounted  for  partly  by  faulting 
along  the  Tertiarj'-Cretaceous  contact  but  is  due,  also,  to  an  unconformable  overlap 
by  the  upper  Miocene  formations  upon  the  older  formations.  Some  time  before  the 
deposition  of  the  upper  Miocene  sediments  the  Table  Mountain  area  was  uplifted 
and  the  Vaqueros  and  Santa  Margarita  (?)  formations  were  entirely  eroded  away. 
At  the  same  time  the  beds  which  now  crop  out  on  the  southwest  flank  of  the  fold 
were  not  eroded  to  any  great  extent.  The  Santa  Margarita  (?)  formation  is  believed 
to  underlie  the  upper  Miocene  to  a  point  considerably  east  of  the  synclinal  axis,  as 
the  shale  crops  out  on  tlie  northeast  flank  of  the  fold  only  a  short  distance  southeast 
of  the  area  shown  on  Plate  XXVIII. 

"Indications  of  oil. — Numerous  seeps  occur  in  this  district  and  are  important  as 
giving  direct  evidence  that  oil  is  present.  The  seeps  are  on  both  flanks  of  the 
Parkfield  syncline,  some  near  the  Table  Mountain  group  of  wells  and  others  north- 
west of  Parkfield,  close  to  and  within  the  San  Andreas  fault  zone. 

"On  the  slope  of  Table  Mountain  from  the  east  boundary  of  the  upper  Miocene 
sandstone  down  to  the  lower  group  of  wells  there  are  numerous  seeps  of  tarry  oil 
in  each  of  the  small  gulches,  and  small  pools  of  nearly  solid  tar  have  collected 
below  the  seeps.  Down  the  canyon  from  the  Table  Mountain  wells,  in  the  eastern 
part  of  Sec.  13,  are  accumulations  of  tar,  indicating  a  former  seep. 

"The  Parkfield  syncline  is  truncated  northwest  of  Parkfield  by  the  San  Andreas 
fault,  and  the  diatomaceous  shale  comes  close  to  the  fault.  In  this  zone  oil  seeps 
are  numerous  and  occur  in  all  the  formations,  even  in  the  granitic  rocks.  Tiie 
following  are  the  principal  ones  seen  : 

"Near  the  center  of  the  north  line  of  the  SEJ  Sec.  9,  T.  23  S.,  R.  14  E..  a  small 
pit  has  been  dug  in  sandstone  immediately  overlying  the  diatomaceous  shale,  and  a 
small   quantity   of   oil   has   collected   in    the   pit. 

"An  almo.^t  continuous  line  of  small  seeps  occur_in  the  Paso  Robles  and  the 
Vaqueros  formations  in  the  bed  of  the  small  creek  which  drains  eastward  across 
the  center  of  the  NWJ  Sec.   5,  T.  23  S.,  R.   14  E. 

"Seeps  of  heavy  oil  occur  every  few  feet  in  a  fault  block  of  crushed  granite 
where  it  is  crossed  bv  the  bed  of  a  small  gulch  that  trends  eastward  and  joins 
Little  Cholame  Creek  about  1000  feet  northeast  of  the  center  of  Sec.  31,  T.  22  S., 
R.  14  E.  Seeps  of  oil  in  granite  are  of  course  very  unusual,  though  in  the  present 
case  no  unusual  explanation  is  necessary  to  account  for  the  facts.  The  granite  is 
a  fault  block  which  was  crushed  and  jointed  by  movements  along  the  San  Andreas 
fault  zone.  Thus  the  normally  impervious  granite  became  sufficiently  porous  for 
oil  to  enter  it  from  adjacent  bodies  of  shale,  in  exactly  the  same  way  that  the  oil 
which  now  seeps  from  the  Paso  Robles  and  Vaqueros  entered  those  formations. 

"Economic  possibilities. — The  Parkfield  syncline  is  the  only  fold  in  this  area  in 
which  any  great  amount  of  the  Santa  Margarita  (?)  formation  is  present  and  in 
which  it  is  overlain  by  a  sufficient  covering  to  retain  any  oil  originally  derived  from 
the  shale.  About  2500  feet  of  upper  Miocene  beds  are  included  in  the  syncline,  and 
oil  might  be  expected  to  occur  at  their  base  on  one  or  both  flanks  of  the  fold.  This 
syncline  could  not  safely  be  condemned  as  barren  of  oil  by  reason  of  the  surface 
evidence,  though  the  flanks  of  an  isolated  syncline  of  this  type  are  not  the  most 
favorable  structure  imaginable. 

"The  Tricounty  well  and  the  Table  Mountain  group  of  wells  have  given  actual 
proof  that  only  small  quantities  of  oil  are  present,  and  as  these  wells  penetrate  the 
beds  most  likely  to  contain  oil  if  it  were  present  at  all,  further  drilling  upon  this 
syncline  would  appear  inadvisable. 


'U.  S.  Geological  Survey.     Bull.  ."iSl-D.     Geology  and  Oil  Prospects  of  the  Waltham, 
Priest,  Bitterwater  and  Peachtree  Valleys,   1914.     By  R.  W.  Pack  and  VV.  A.  English. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  93 

"Unfavorable  results  were  also  obtained  by  test  wells  in  the  Vallecitos,'  an  area 
norlliwest  of  Coalinga,  in  which  the  structure  is  essentially  similar  to  that  of  tin- 
I'arkfioKl  svncline.  Tlie  tests  of  those  two  areas  go  far  toward  jiroving:  tluit  isolated 
synflines  oi"  the  oil-btariug  series,  surrounded  by  older  rocks,  will  not  prove  productive  , 
in  ralifornia.  There  are  three  factors  which  may  account  for  the  lack  of  oil. 
First,  there  may  be  an  insutlicient  amount  of  shale  present  to  have  originally 
furnished  any  large  quantity  of  oil.  Second,  the  oil  originally  present  could  not 
be  greatly  concentrated  at  certain  points,  as  migration  could  take  place  only  along 
the  coniparativtly  short  distance  between  the  axis  of  the  synclinc  and  the  outcrops 
of  the  oil  sands  on  the  Hanks  of  the  fold.  In  contrast  are  the  productive  San 
Joaquin  Valley  fields,  where  the  oil  in  the  productive  folds  may  have,  come  from" 
areas  far  out  in  the  valley  syncline  and  also  have  migrated  up  the  rise  in  anticlines. 
The  third  factor  is  the  probable  loss  of  oil  at  the  outcrop  of  the  oil  sands.  In  an 
isolated  syncline  there  is  nothing  to  prevent  the  oil  migrating  up  the  dip  and 
escaping  at   the  outcrop. 

"Wells  drilled  for  oil. — In  the  following  descriptions  of  wells  the  numbers  corre- 
spond to  those  on  the  geologic  map  of  the  Parkfield  area  (PI.  XXVIII)."  (See  end  of 
article   for   locations.)  : 

"At  the  localities  numbered  1  and  2  remnants  of  rig  timbers,  etc.,  probably 
represent  old  holes  drilled  by  Captain  Barrett  and  associates  before  year  1900.  The 
locations  are  unfavorable. 

"Well  No.  3,  the  Oakshade  well,  owned  by  the  Monterey  Oil  Co.,  is  said  to  have 
been  drilled  to  a  depth  of  1910  feet  and  to  have  encountered  some  oil  and  ga.s.  This 
well  is  situated  in  the  zone  of  complicated  structure  along  the  San  Andreas  fault. 
Such  wells  generally  produce  showings  of  oil  but  not  enough  to  make  them  successful. 

"Well  No.  4  ind'icates  the  location  of  the  Middle  Ridge  Oil  Company's  derrick. 
No  drill ing  has  been  done  here  and  there  is  little  chance  of  obtaining  oil  at  this 
locality. 

"Well  No.  5,  the  Tricounty  well,  is  said  to  have  reached  a  depth  of  4160  feet  and 
found  showings  of  oil  at  several  depths.  The  well  starts  in  upper  Miocene  sandstone 
and  reaches  the  underlying  Santa  Margarita  (?)  formation  near  the  bottom. 
Although  there  was  some  water  trouble,  which  might  account  partly  for  the  failure 
to  obtain  much  oil,  this  well  furnishes  a  pretty  fair  test  of  the  west  flank  of  the 
Parkfield   syncline. 

"Well  No.  6,  tlie  Parkfield  Syndicate  well,  was  drilled  with  a  portable  rig  to  a 
depth  of  500  feet  and  got  a  small  amount  of  gas.  It  was  drilled  entirely  in  the 
Vaqu-  ros   sandstone. 

"Well  No.  7,  the  Miller  or  Raymond  well,  was  the  first  of  the  Table  Mountain 
group  of  wells,  as  drilling  is  said  to  have  been  started  in  188S.  The  drill  is  said  to 
have  reached  a  depth  between  640  and  80  0  feet  without  passing  through  any  oil  or 
tar  sands.  Sulphur  water  is'now  llowing  from  the  casing.  Of  the  wells  of  the  Table 
Mountain  Oil  Co.,  Nos.  8  and  9  are  270  and  600  feet  deep  respectively.  They  arfe 
said  to  be  in  oil  or  tar  sand  for  most  of  this  depth.  Wells  Nos.  10,  11  and  12  are 
sliallow,  ranging  from  100  to  200  feet  in  depth  ;  they  are  now  abandoned,  and  when 
the  writer  visited  them  water  and  a  small  quantity  of  oil  stood  within  25  to  50  feet 
of  the  top  of  the  casing  in  each  well.  The  Table  Mountain  wells  are  said  to  have 
nroduced  a  few  barrels  of  oil  per  day  at  the  lime  of  their  completion.  The  oil 
doubtless  originated  in  the  Santa  Margarita  (?)  formation  and  migrated  up  along 
the  fault  which  lies  east  of  these  wells,  saturating  the  sands  for  a  few  bundled 
feet  out  from  the  fault.  The  base  of  the  uiiper  Miocene  sandstone  also  probably 
contains  some  oil  which  has  migrated  directly  up  from  the  underlying  shale,  in 
addition   to   that   which   came  up  along  the   fatdt   plane. 

"Well  No.  13,  sometimes  called  the  Livermore  well,  was  drilled  by  the  Future 
Success  Oil  Co.,  ,ln  1913-14.  It  reached  a  depth  of  1810  feet,  mostly  in  Cretaceous 
shai^;  but  also  apparently  passing  through  intrusive  sheets  of  serpentine  and  possibly 
reaching  Franci.scan  rocks  near  the  bottom.  This  well  is  separated  from  those  on 
the  west  by  a  fault,  and  the  light-gravity  oil.  showings  of  which  are  said  to  have 
been  encountered,  originated  in  the  Cretaceous  shale.  Wells  drilled  in  the  dark 
Cretaceous  shale  generally  get  showings  of  a  light-gravity  oil  but  only  a  very  small 
quantity. 

"Well  No.  14,  the  Dominion  well,  was  drilled  in  1912  nnd  is  .said  to  be  between 
150  and  300  feet  deep.  It  is  located  in  an  area  of  .serpentine  slide,  near  the  contact 
between  the  serpentine  and  the  Cretaceous  rocks.  The  bailer  dump  (consisting  of 
the  drill  cuttings)  appears  to  be  made  up  entirely  of  serpentine,  but  some  Cretaceous 
shale  may  have  been  encountered.     The  location  is  unfavorable." 

AYell  No.  1  is  located  about  the  center  of  Sec.  32,  T.  22  S.,  R.  14  E. 

Well  No.  2  is  located  in  the  SE.  -}  of  Sec.  5,  T.  23  S.,  R.  14  E. 

AVell  No.  3  is  located  near  the  north  quarter-corner  of  Sec.  8,  T.  23 

'Veil  No.  4  is  located  in  the  NE.  ]  of  See.  18,  T.  23  S.,  R.  14  E, 
Well  No.  5  is  located  in  the  SE.  ^  of  Sec.  15,  T.  23  S.,  R.  14  K 

^Anderson.    Robert,    and    Pack.    R.    W.     Geology    and    Oil    Resources    of    the    Weirt  - 
Border    of    the    San    .loanuin    Vallev.    North    of    Coalinga,    Cal.      U.    S.    Geol.    Survey^ 
Bull  603.      Pp.   167-177,  1915. 


94  CALIFORNIA    PTATE    MINING   BUREAU. 

Well  No.  6  is  located  in  the  NE.  ]  of  See.  26,  T.  23  S.,  R..14  E. 
Wells  Nos.  7,  8,  9,  10,  11  and  12  are  loeated  in  the  SE.  i  of  Sec.  13,  T. 
23  S.,  R.  14  E. 
Well  No.  13  is  loeated  in  the  SE.  ]  of  See.  18,  T.  23  S.,  R.  15  E.. 
Well  No.  14  is  loeated  in  the  NE.  ]  of  See.  19,  T.  23  S.,  R.  15  E. 

San    Luis  Obispo   County. 

That  portion  of  the  connty  lying  north  of  San  Lnis  Obispo  and  west 
of  the  Salinas  Valley  is  a  nigged  mountainoas  area  of  the  Santa  Lucia 
Range.  The  rocks  along  the  western  portion  are  mainly  sandstones, 
cherts  and  serpentine  of  the  Franciscan.  On  the  eastern  slope  which 
drain.s  into  the  Salinas  Valley,  beds  of  sandstone  and  shale  of  C'retaceons 
age  are  exposed  together  with  overlying  beds  of  sandstone  and  shale 
of  tlie  ^Monterey  Series     There  is  no  evidence  of  petroleum  in  this  district. 

In  the  Salinas  Valley  proper,  between  the  ^Monterey  Connty  line  and 
Templeton,  the  formations  ex[)osed  are  l)eds  of  sand  and  gravel  of  the 
Paso  Rol)les  formation,  with  an  aiea  of  granite  to  the  northwest  of  the 
town  of  Paso  Robles.  The  Paso  Rol)les  beds  are  practically  flat  lying 
with  the  exception  of  an  area  northeast  of  San  Miguel,  where  the  south- 
ea.st  end  of  the  Bradley  anticline  is  found.  The  only  oil  possibilities  lie 
along  the  axis  of  this  fold  (see  page  89  for  description).  However,  in 
view  of  the  fact  that  the  Shell  Company's  well  in  See.  32,  T.  24  S.,  R. 
12  E.,  ]Monterey  County,  located  on  the  axis  of  the  fold,  has  reached  a 
depth  of  4200  feet,  with  only  a  small  showing,  makes  the  outlook  for 
production  unfavorable. 

The  Salinas  Valley  from  Templeton  to  Cuesta  Pa.ss  becomes  very  nar- 
row, the  formations  exposed  consist  of  small  thicknesses  of  highly- 
crushed  diatomaceous  shale  and  sandstone  of  the  ^Monterey  Series, 
overlaid  by  small  patches  of  tine  white  sandstone  and  diatomaceous  shale 
of  the  Santa  jNIargarita.  On  the  west  these  formations  rest  against  the 
Cretaceous  and  Franciscan  and  in  the  east  against  a  granite  area.  The 
district  is  unfavorable  for  the  accumulation  of  oil. 

That  portion  of  the  county  lying  east  of  the  Salinas  Valley  and  north 
of  a  line  running  due  east  through  Atascadero  is  mainly  an  area  of  low, 
rolling  hills  drained  by  Estrella  and  San  Juan  creeks.  The  formations 
exposed  consist  mainly  of  Hat-lying  beds  of  sand,  gravel  and  clay  of 
Pliocene  age.  In  the  extreme  northeast  corner  near  Chalome,  there  is 
a  small  area  of  Cretaceous  and  ^Monterey.  In  the  Red  Hills,  which  lie 
southeast  of  Shandon,  English^  has  reported  that  pre-Franciscan  rocks 
are  present,  and  McLaughlin  and  Waring-  have  reported  the  presence  of 
jMonterey  shale  and  Vaqueros  sandstone.  Southeast  of  Creston  in  T.  28 
S.,  R.  14  E.,  ])eds  of  the  Santa  ^Margarita  formation,  together  with  sand- 
stone and  shales  beds  of  the  Monterey  Series  are  reported  as  overlying 
the  granites  of  the  east  slope  of  the  Santa  Lucia  Range.  From  these 
outcrops  it  is  apparent  that  the  ^Monterey  Series  is  probably  present 
beneath  the  Pliocene,  over  a  large  portion  of  this  area,  and  therefore  this 
region  fulfills  two  of  the  conditions  for  the  accumulation  of  oil :  that  is, 
there  are  porous  beds  (Pliocene)  overlying  beds  of  diatomaceous  shale 
(^Monterey).  However,  other  conditions  are  unfavorable  and  it  is  not 
likely  that  oil  in  commercial  quantities  will  be  found  here.     This  state- 


'Geolosv  and  Oil  Prospects  of  tlie  Sulinas  VaUey-Parkfield  Area.  By  W.  A.  Engli.sli. 
1918,  p.  246. 

■■HZ'alifornia  Stato  Mining  Bureau.  Bull.  G:i.  By  R.  P.  McLaughlin  and  C.  A.  Waring. 
Map  folio  Plate  IV,   1914. 


PETROI-ErM    RESOURCES   OF    CALIFORNIA.  95 

inent  is  based  on  the  fact  that  favorable  .slnict  iiic  is  entirely  lacking  and 
the  basal  beds  of  the  Pliocene  show  no  seepages,  iioi-  does  the  Monterey 
shale  show  any  evidence  of  petroleum.  In  additiiui.  tlic  same  facts  hold 
true  here  as  elsewhere  in  the  Salinas  Valley  area;  that  is,  the  Pliocene 
beds  do  not  contain  any  appreciable  amount  of  oil  and  the  Monterey 
contains  only  very  small  (|uantities.  As  stated  before,  this  is  due  to 
the  uplifting  and  erosion  of  the  ^Monterey  with  a  loss  of  the  oil  content 
before  the  dei)()sition  of  the  Pliocene  beds.  A  nuip  of  this  area  will  be 
found  in  the  folio  accompanying  Bulletin  69  of  the  State  iMining  Bureau. 

The  area  between  Atascadero  on  the  north  and  the  Santa  jNIaria  Valley 
on  the  south  and  between  K.  13  E.  and  1ho  (Mtast  has  been  mapped  in 
detail  by  Fairbanks^ 

From  San  Luis  Obispo  in  a  northwest  direction  this  area  is  covered 
with  metamorphie  rocks  ol'  tlie  Fi'aneisean,  and  the  Santa  Lucia  Range 
east  of  Santa  Mai'garita  is  composed  of  granite.  The  only  possible  oil 
districts  consist  of  two  parellel  areas  of  .Monterey  shale.  One  in  the 
main  Santa  Lucia  Range,  running  southeast  from  Cuesta  Pass  down 
Lopez  Canyon,  and  the  second  located  in  the  San  Luis  Range  wdiich 
borders  the  coast  south  of  San  Luis  Obispo.  Both  these  areas  are 
synclinal  in  structure  and  the  axis  of  the  anticline  which  once  separated 
them  ran  down  the  San  Luis  Valley  and  has  been  eroded  down  to  the 
underlying  crystalline  rocks.  The  shale  in  the  area  around  Lopez  Can- 
yon is  highly  tilted,  the  limbs  of  the  syncline  having  an  average  dip  of 
about  50°.  Seepages  of  oil  have  l)een  reported  and  there  is  no  doubt 
but  what  there  is  sufficient  diatomaceous  shale  present  to  have  formed 
considerable  oil.  This,  however,  probably  collected  in  the  beds  that 
formed  the  axis  of  the  anticline  along  the  San  Luis  Valley  and  wliich 
have  been  removed  by  erosion.  The  lack  of  any  reservoir  beds  overlying 
the  shale  and  the  unfavorable  structure,  condemns  this  area  as  a  possible 
producer  of  an  appreciable  amount  of  oil. 

The  area  of  IMonterey  shale  in  the  San  Luis  Range  runs  from  Point 
Buchon,  just  soutli  of  Morro  J^ay,  in  a  southea.st  direction  to  the  Arroyo 
Grande  Valley  The  structure  is  a  syncline  with  the  axis  striking  south 
30°  east.  The  northeast  limb  rests  on  the  crystalline  rock  of  the  Fran- 
ciscan along  the  San  Luis  Valley  and  the  southwest  limb  rests  on  similar 
rocks  along  the  coast  line.  From  Point  Huchun,  southeast  to  San  Luis 
Obispo  Creek,  the  IMonterey  is  not  overlaid  by  any  younger  formation, 
and  there  is  no  noticeable  evidence  of  petroleum.  From  San  Luis  Obispo 
Creek,  southeast  to  the  Arroyo  Grande  Valley,  the  Monterey  is  overlaid 
along  the  middle  of  the  syncline  by  the  Pismo  formation.  It  is  in  this 
area  that  prominent  indications  of  oil  occur  and  the  Arroyo  Grande  oil 
field  is  located. 

ARROYO  GRANDE  OIL  FIELD. 

The  principal  devel()i)ment  is  along  Pismo  ("I'eek,  al^out  three  miles 
north  of  Pismo.  In  December,  1920,  seventeen  wells  were  pumping  in 
the  field,  operated  mainly  by  the  Associated  Oil  Company.  The  average 
production  per  well  is  about  nine  bai'i'cls  per  day  and  the  total  lu'oduction 
from  the  field  from  July  1,  1!)20.  to  December  ;J1,  1920,  averaged  about 
170  barrels  per  day  of  14°  Baume  gravity  oil. 

'United  States  Geological  Survey.      San  Luis  folio  lOL     By  H.  W.  Fairbank.s,  1904. 


96  CALIFORNIA   STATE   MINING  BUREAU. 

The  major  portion  of  the  wells  are  located  on  the  north  flank  of  the 
svn(^line,  the  axis  of  which  passes  just  south  of  California  Oil  Company 
Well  No.  3,  striking  S.  30°  E. 

The  oil  has  originated  in  the  IMontcrey  shale  auii  lias  eolleeted  in  the 
overlying  sands  of  the  Pismo  formation.  The  dips  on  both  tianks  of  the 
syncline  in  the  Pismo  sandstone  average  about  20° ;  the  dips  in  the 
underlying  ^Monterey  are  about  60°.  The  Pismo  formation  named  by 
Fairbanks^  consists  in  this  area  mainly  of  coarse  loose  sands  with  lentic- 
ular beds  of  shale.  It  may  be  correlated  with  the  Santa  ^largarita  for- 
mation (upper  Miocene).  The  logs  of  wells  drilled  along  the  axis  of 
the  syncline  sliow  it  to  be  about  2000  feet  thick.  The  lack  of  any  contin- 
uous shale  bodies  which  would  confine  the  oil  to  certain  sands,  has  resulted 
in  tlie  oil  being  disseminated  tiircughout  the  entire  2000  feet  of  sand  in 
a  lean  saturation.  This,  together  with  the  fact  that  the  structure  con- 
sists of  an  unsealed  syncline,  aeeoiuits  for  the  .small  production.  It  is 
not  likely  that  the  production  or  the  limits  of  tlie  field  will  ever  he 
greatly  increased   over   their   present   status. 

There,  however,  is  present  another  possibility  which  may  prove  profit- 
able in  time.  That  is  tlie  mining  and  distillation  of  the  bituminous 
sands  of  the  Pismo,  which  are  to  lean  to  give  profitable  welh  but  whicli 
might  in  time  be  Avorth  distilling.  These  sands  outcrop  along  the  north 
limb  of  the  syncline  just  south  of  Edna  and  have  at  various  times  been 
mined  for  asphaltum.  A  recent  test  shows  that  they  yield  about  twenty- 
five  gallons  of  20°  Baume  gravity  oil  per  ton.  In  addition  to  San  Luis 
folio  101,^  reports  on  this  area  have  been  made  by  Eldridge-  and  the 
Mining  Bureau.^ 

The  country  lying  south  of  Arroyo  Grande  to  the  Santa  Barbara 
County  line  consists  mainly  of  low  rolling  hills,  with  the  Xipomo  Valley 
in  the  eastern  portion.  The  rocks  exposed  con.sist  of  loose  sands  and 
gravels  of  the  Paso  Eobles  formation,  together  with  recent  terrace 
deposits.  Neither  of  these  formations  has  a  thickness  of  more  than  a 
few  hundred  feet  and  the  underlying  Franciscan  serpentine  outcrops 
frecpiently  over  the  area.  The  region  oflfers  no  possibility  of  having  oil. 
The  hills  that  form  the  northeast  edge  of  the  Nipomo  Valley  and  which 
are  known  as  the  Nipomo  Hills  consist  of  rhyolite  tuff  and  diatomaceous 
shale  of  the  ^lonterey  Series.  These  hills  will  be  discussed  in  the  article 
on  theHuasna  District. 

HUASNA   DISTRICT.* 

This  area  lies  to  the  south  and  east  of  Arroyo  Grande  and  consists 
of  the  territory  around  Tar  Spring  Creek.  Arroyo  Grande  Creek.  Iluasna 
Valley,  Alamo  Creek  and  Suey  Creek.  The  Nipomo  quadrangle  of  the 
United  States  Geological  Survey  covers  the  major  portion  of  the  area. 

The  formations  exposed  consist  mainly  of  the  Monterey  Series.  The 
two  areas  of  ^Monterey  shale  described  in  the  preceding  paragraphs 
and  which  form  the  two  svnclinal  structures  along  Lopez  Canyon  ami 


'United  States  Geological  Survey.     San  Luis  folio  101.     By  H.  W^  Fairbanl<s. 

=Twentv-second  Annual  Report  of  the  LT.  S.  Geolosical  Survey.  Part  I.  Pages  412- 
424.     AsphaU  and  bituminous  rock  deposits.     By  G.   H.   Eldridge.     1900. 

^California  State  Mining  Bureau.     Bulletin  69.     Pages  430-432. 

♦The  writer  is  indebted  to  Mr.  F.  Tickell  of  the  Southern  Pacific  Company  for  the 
major  portion  of  the  data  in  this  area. 


PETROLEUM    RESOURCES   OP    CALIFORNIA.  97 

in  the  Arroyo  GraiKle  field  incru'e  in  the  Iluasiia  Distriet.  The  body 
of  the  FraiU'isean  formation  whieh  separated  them  along  the  San  Luis 
Valley  is  faulted  out  of  sight  at  a  point  on  Tar  Spring  Creek  about  one 
mile  southwest  of  the  Tar  Springs  Ranch.  In  the  Nipomo  Hills,  which 
form  the  southwestern  portion  of  the  district  and  which  lie  between  the 
Huasna  Valley  and  the  Nipomo  VaHey,  the  basal  beds  of  the  Monterey 
are  exposed.  These  consist  of  silicified  rhyolite  tuff,  overlying  the 
Franciscan  on  the  western  slope  of  the  hills.  Above  the  tuff  beds  and 
forming  the  top  of  the  ridge  are  beds  of  diatomaceous  shale,  with 
some  sand.stone.  The  gveneral  dip  is  about  40^  to  the  northeast, 
although  there  are  numerous  sharp  minor  anticlines  along  the  north 
slope  of  the  hills,  where  they  descend  into  Tar  Spring  Creek  and  the 
ITuasna  Valley. 

The  general  structure  in  the  upper  portions  of  the  Huasna  Valley  is 
synclinal  and  the  ]\Ionterey  beds  dip  under  the  Santa  Margarita  sand- 
stone, which  occupies  an  area  of  about  five  square  miles  between  Musick 
and  the  Ilua.sna  School  On  the  east  side  of  this  synclinal  trough,  the 
Monterey  along  the  Huasna  River  rests  upon  a  small  thickness  of 
Vaqueros  which  in  turn  rests  on  the  Cretaceous,  which  forms  the  core 
of  the  Santa  Lucia  Range  in  this  distriet 

While  the  general  structure  of  the  Huasna  Vallej^  is  synclinal  the 
following  minor  folds  occur,  beginning  from  the  west :  A  syncline  in  the 
Santa  Margarita  running  northwest  through  Tar  Spring  Ranch;  an 
anticline  in  the  Santa  Margarita  running  northwest  along  the  high  ridge 
north  of  the  Tar  Springs  Ranch;  a  syncline  in  the  Santa  ^Margarita  run- 
ning northwest  from  the  Park  Ranch,  and  finally  an  anticline  partly 
in  the  Vaqueros  and  partly  in  the  JMouterey  running  northwest  in  the 
hills  east  of  the  Huasna  River 

Indications  of  oil  are  found  in  seepages  in  the  Monterey  along  Suey 
Creek,  Tar  Spring  Creek  and  in  the  Nipomo  Hills.  In  the  Santa  Mar- 
garita north  of  the  Tar  Springs  Ranch  there  are  outcrops  of  bituminous 
sands.     The  following  wells  have  been  drilled  in  this  area: 

The  Doheny  Well  No.  1,  located  on  Tar  Spring  Creek,  about  one- 
fourth  of  a  mile  southwest  of  the  Tar  Spring  ranchhouse.  A  depth  of 
875  feet  was  reached  and  a  showing  of  gfis  obtained.  The  Stow  Well 
of  the  Associated  Oil  Company,  located  on  Suey  Creek,  reached  a  depth 
of  about  1500  feet  in  the  Monterey,  at  whieh  point  serpentine  was  encoun- 
tered. The  Associated  Oil  Company  drilled  a  well  in  the  NE.  }  of  Sec.  1, 
T.  32  S.,  R.  14  E. ;  a  depth  of  3675  feet  was  reached  without  obtaining 
production.  In  the  SW.  i  of  Sec.  7,  T.  32  S.,  R.  15  E.,  is  an  old  aban- 
doned hole  know  as  the  ]\IcKay  Well. 

The  Stieger  Well  was  drilled  on  the  Porter  Ranch  in  what  would  be 
the  SW.  i  of  Sec.  35,  T.  31  S.,  R.  15  E.  A  depth  of  1100  feet  was  reached 
without  any  showings. 

The  Ilarkness  wells  No.  2  and  No.  3  are  located  about  one  and  one- 
fourth  miles  south  of  the  Porter  ranchhouse  on  the  east  side  of  the  Huasna 
River.     A  depth  of  1000  feet  was  reached  without  any  showings. 

The  Harkness-Squires  wells  No.  4  and  No.  5  are  located  about  one 
mile  northeast  of  the  Porter  Ranch.  A  depth  of  about  800  feet  was 
reached  and  a  little  gas  was  encountered. 

The  Downer  wells  No.  1  and  No.  2  were  drilled  in  the  SE.-^  of  Sec.  31, 
T.  32  S.,  R.  16  E.     No  oil  was  encountered. 

7—13322 


98  CALIFORNIA    STATE    MINING   BUREAU. 

The  sharply  tilted  couditiou  of  the  Monterey  shale,  together  with  the 
lack  of  any  large  amount  of  reservoir  beds  overlying  the  diatomaceous 
shale,  make  this  area  unfavorable  for  the  accumulation  of  oil  in  any 
appreciable  amounts.  If  any  further  drilling  is  done,  the  most  favorable 
locality  for  the  location  of  a  well  is  along  the  axis  of  the  anticline  in  the 
Santa  iMargarita  sandstone  which  marks  the  high  ridge  to  the  northeast 
of  the  Tar  Springs  ranchhouse. 

The  general  mountainous  region  that  lies  east  of  San  Luis  Obispo, 
Arroyo  Grande  and  the  Cuyama  Valley  and  west  of  San  Juan  Creek  and 
the  Carrizo  Plains  may  be  regarded  a.s  the  extreme  southeast  extension 
of  the  Santa  Lucia  Range.  The  northern  portion  in  the  vicinity  of  Poso 
and  La  Panza  is  known  as  the  La  Panza  Range.  The  southern  end, 
which  forms  the  divide  between  the  Carrizo  Plains  and  the  Cuyama 
Valley,  is  known  as  the  Caliente  Range.  The  areas  around  Arroyo 
Grande,  Lopez  Canyon  and  the  Huasna  District,  may  properly  be  con- 
sidered as  belonging  to  the  western  portion  of  the  region,  but  on  account 
of  indications  of  petroleum  they  are  discussed  separately  in  the  pre- 
ceding paragraphs. 

Aside  from  these  areas  the  region  contains  no  indications  of  petroleum. 
The  major  portion  has  been  mapped  by  the  state^  and  a  portion  of  the 
southwestern  slope  of  the  Caliente  Range  by  the  Geological  Survey.-  The 
general  geology  is  as  follows :  In  the  northern  portion  between  La  Panza, 
Pozo  and  Atascadero  the  formations  are  granite.  The  core  of  the  range 
south  of  Pozo  and  east  of  ^Musick  is  composed  of  sharply-dipping  Creta- 
ceous rocks.  In  the  southern  portion,  the  core  of  the  Caliente  Range  is 
mainh'  Cretaceous  and  the  east  and  west  slopes  are  composed  of  highly 
tilted  areas  of  Vaqueros  sandstone,  ]\Ionterey  shale  and  Santa  ]\Iargarita 
sandstone  and  shale. 

The  highly -tilted  and  faulted  condition  of  the  sedimentary  rocks  in 
tlie  southern  and  central  portion  and  the  crystalline  character  of  the 
rocks  in  the  northern  portion  make  the  district  an  unlikely  place  for 
the  accumulation  of  oil. 

DISTRICT    OF    THE    CARRIZO    PLAINS    AND    SAN   JUAN    CREEK. 

This  district  occupies  the  eastern  portion  of  the  county  and  forms  an 
area  of  low  rolling  hills  and  plains  between  the  Santa  Lucia  Range  on 
the  west  and  the  Temblor  Range  on  the  east. 

The  western  and  southern  portioiLs  have  been  mapped  by  iMcLaughlin 
and  Waring^  and  the  eastern  and  northern  parts  by  Arnold.* 

The  geology  according  to  these  reports  is  as  follows :  Along  the  upper 
portion  of  San  Juan  Creek,  north  of  the  San  Juan  Ranch,  the  beds 
exposed  consist  of  loose  sands  and  clays  of  the  Paso  Robles  formation, 
practically  flat  lying.  The  country  is  similar  to  the  region  around  Shan- 
don.  From  the  San  Juan  Ranch  south  along  San  Juan  Creek  to  a  point 
on  a  line  between  La  Panza  and  Simmler,  the  principal  formation  exposed 

'California  State  Mining  Bureau.  Bull.  69.  Map  folio  Plate  IV,  1914.  By  R.  F. 
McLaughlin  and  C.  A.  Waring. 

^United  States  Geological  Survev.  Geology  and  Oil  Prospects  of  the  Cuyama  Valley. 
Bull.  621-M,   1916.      \V.  A.  English. 

^California  State  Mining  Bureau.  Bull.  69.  Petroleum  Industry  of  California,  1914. 
By  R.  P.  McLauglilin  and  C.  A.  Waring.      Pp.  429-430,  map  folio  Plate  IV. 

^United  States  Geological  Survey.  Bull.  406.  Preliminary  Report  on  the  McKittrick 
Sunset   Oil   Region,    1910.     By  R.    Arnold   and   H.   R.    Johnson. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  99 

is  the  Santa  ^larsrarita.  It  is  overlaid  in  small  ai-cas  by  i)atehes  of 
the  Paso  Roblos  formation  and  occasionally  the  nndcrlying  ^lonterey 
shale  is  exposed.  The  structure  consists  of  a  number  of  rather  sharply- 
folded  northwest  and  southeast  striking  anticlines.  A  seepage  of  oil  is 
reported  in  the  basal  sands  of  the  Santa  ^Margarita  near  the  north  line 
of  See.  23,  T.  29  S.,  R.  17  E.  In  the  center  of  Sec  29.  T.  28  S.,  R.  17  E., 
a  well,  known  as  the  Cedar  Spring  Well,  wa.s  drilled  to  a  depth  of  1960 
feet  in  1914  and  no  oil  was  encountered.  At  the  present  time  the  well 
is  being  deepened.  It  is  located  approximately  on  the  axis  of  an  anti- 
cline in  the  Santa  Margarita  and  should  ofl'ei-  an  excellent  test  of  this 
region. 

The  west  side  of  the  Carrizo  Plains  from  Sinnnler  south  is  composed 
mainly  of  beds  of  the  Monterey  Series,  with  the  Vaqueros  sand.stone 
predominating.  The  shale  beds  of  the  series  are  best  exposed  in  the 
hilLs  west  of  the  Painted  Rock  rauchhouse.  In  the  extreme  southwestern 
portion,  the  McKittrick  sands  and  gravels  are  lying  directly  on  the 
Vaqueros.  The  entire  region  is  sharplv  folded  into  a  number  of  anti- 
clines. On  Sec.  12,  T.  11  X.,  R.  2(i  W.,  E.  (!.  Lewis  is  now  drilling 
a  well. 

The  flat  central  portion  of  the  Carrizo  Plains  is  covered  by  loose  sands 
and  conglomerates,  probably  corresponding  to  the  Paso  Robles  formation. 

The  dominant  feature  of  the  eastern  side  of  the  plains  is  the  San 
Andreas  Fault.  In  the  southern  end,  it  is  marked  by  the  sharp  fault 
sf'arp  on  the  west  edge  of  the  Elkhorn  Hills  and  in  the  north  end  it 
forms  the  Bitterwater  Valley  and  Palo  Prieto  Pass. 

The  area  between  the  fault  zone  and  the  ridge  of  the  Temblor  Range 
which  marks  the  eastern  border  of  the  county,  is  intensely  crushed  and 
broken.  The  formation  consists  of  Vaqueros  sandstone,  Monterey  shale 
and  Paso  Robles  sands.  South  of  San  Diego  Joe's  Ranch  there  are 
innumerable  small  sharply-folded  anticlines  in  the  Vaqueros  aiul  j\Ion- 
terey  ;  and  in  the  outcropping  beds  of  these  formations  there  are  numerous 
seepages  The  oil  probably  originated  in  the  Blonterey  shale  and  has 
collected  in  the  interbedded  sands  of  this  formation  and  in  the  Vaqueros 
sandstone  by  reason  of  faulting. 

North  of  San  Diego  Joe's  Ranch  the  structure  is  not  so  broken  and 
there  are  no  seepages.  In  Sec.  20,  T.  29  S.,  R.  19  E.,  the  Associated  Oil. 
Company  drilled  a  well  to  a  depth  of  about  31:00  feet  in  1918  and  failed 
to  obtain  any  indications  of  oil.  The  well  is  apparently  loc^ated  close  to 
the  fault  zone.  The  general  possibilities  may  be  summed  up  as  follows: 
Along  San  Juan  Creek  and  the  west  side  of  the  Carrizo  Plains  the  general 
geological  conditions  are  not  very  favorable  for  the  accumulation  of 
petroleum  and  there  are  no  indications  of  oil  except  in  Sec.  23,  T.  29  S., 
R.  17  E.,  as  noted  above.  However,  the  region  ls  worthy  of  being  exam- 
ined further  in  detail  before  absolutely  condemning  it. 

Along  the  east  side  of  the  plains,  south  of  San  Diego  Joe's  and  east 
of  the  fault  zone,  it  is  probable  that  small  amounts  of  oil  can  be  obtained 
from  wells  drilled  along  the  axis  of  the  numerous  folds  of  this  area;  but 
whether  any  well  would  be  of  commercial  value,  can  only  be  told  by 
drilling.  _j 


100  CALIFORNIA    STATE    MINING   BUREAU. 

In  the  country  north  of  San  Diego  Joe's  there  is  apparently  no  indi- 
cation of  oil.  Following  is  a  portion  of  McLaughlin  and  AVaring's 
report : 

"The  two  Smith  wells  were  drilled  along  an  anticline  of  Monterey  sandstone,  south- 
east of  San  Diego  Joe's.  One  of  these  is  near  the  northwest  corner  of  Sec.  22,  T.  30  S., 
R.  20  E.,  and  the  other  near  the  northwest  corner  of  Sec.  16,  T.  30  S.,  R.  20  E.  Only 
traces  of  oil  were  struck. 

"The  Erume  well  was  drilled  200  feet  into  the  faulted  zone,  near  Sulphur  Spring 
fault,  through  the  Monterey  shale  into  the  Monterey  sandstone  of  Sec.  15,  T.  31  S., 
R.   21  E.     Some  light  oil  was  obtained  but  not.  in  paying  quantity. 

"The  Recruit  well  was  driled  1530  feet  into' the  Monterey  sandstone,  or  possibly  in 
faulted  formation.      No  oil  was  obtained. 

"The  Humauma  well  was  drilled  2300  feet  into  the  Monterey  sandstone.  Only  a 
trace  of  oil  was  obtained. 

"The  Vishnu,  or  Sperry  well  struck  some  oil  but  has  never  produced  enough  oil  to 
market.     It  is  driled  on  a  monocline  in  the  Monterey  formation. 

"On  the  southwest  flank  of  the  Temblor  Range  some  oil  has  been  obtained  by  wells 
in  the  Monterey  sandstone.  The  oil  is  of  good  gravity,  but  probably  will  not  be  found 
in  commercial  quantities,  owing  to  intense  folding  and  faulting.  Some  oil  may  possibly 
be  found  east  of  the  San  Andreas  rift  in  the  region  of  the  Panorama  Hills;  however, 
the  Humauma  wpII  was  unsuccessful,  although  located  in  a  favorable  locality  to  test 
the  neighborhood." 

Following  are  portions  of  the  Arnold  and  Johnson  report : 

"The  region  generally  known  as  the  'Carrizo  Plain  District'  embraces  Carrizo  and 
Elkhorn  plains  and  the  adjacent  southwestern  flank  of  the  Temblor  Range.  The  sup- 
posed oil  territory  occupies  the  flanks  of  the  hills  toward  the  base  of  the  range  and 
the  edge  of  the   Carrizo  and  Elkhorn  plains. 

"Geology. 

"Tlie  oil  in  the  Carrizo  Plain  District  occurs  in  sandstones  interbedded  with  the  base 
of  tlie  Monterey  shale,  or  at  the  top  of  the  Vaqueros,  or  in  beds  unconformably  over- 
lying the  Monterey  and  Vaqueros.  The  Variueros  sandstones  are  coarse  and  consist 
largely  of  quartz  grains,  with  occasional  gi-anite  and  black  to  varicolored  quartzite 
pebbles.  The  sandstone  is  roughly  concretionary,  the  concretions  sometimes  attain- 
ing a  diameter  of  10  or  15  feet.  The  beds  carrving  oil.  which  unconformably  overlie 
the  Vaqueros  and  Monterey,  consist  of  granitic  debris  and  rounded  shale  fragments. 
Tlie  shallow  wells,  of  whicli  all  the  successful  ones  penetrate  the  base  of  tlie  Monterey, 
or  the  ton  of  tlie  Vaqueros,  have  in  most  instances  been  put  down  close  to  tlie  axis 
of  those  anticlines  which  have  an  arched  top  and  steep-dipping  sides.  There  are 
several  of  these  anticlines  (shown  on  tlie  map,  plate  1)  which  expose  the  Vaqueros 
sandstone  or  bring  it  close  to  the  surface.  Faults  accompany  most  of  the  anticlines, 
and  so  complicate  the  structure  that  predictions  concerning  the  territory  a  short 
distance  away  from  the  axis  of  an  anticline  are  extremely  hazardous. 

"An  oil  sand  consisting  of  shale  and  other  pebbles  associated  with  granitic  sand, 
and  believed  to  be  of  later  age  than  the  Mo!iterey,  is  exposed  in  the  southern  part  of 
the  area.  A  particularlv  advantageous  place  for  studying  this  is  about  one-half  mi'.e 
west  of  the  Vishnu  well,  in  the  southern  part  of  Sec.  22,  T.  32  S.,  R.  22  E.  Tlie  sand 
here  is  probably  over  15  or  20  feet  thick,  and  is  overlain  by  fine-grained  brown  shales. 
This  oil  sand  lies  in  a  syncline,  near  the  eastern  edge  of  which  the  Vishnu  well  has 
been  put  down.  It  is  believed  that  the  Vishnu  well  obtains  its  oil  from  the  Monterey 
•  or  Vaqueros  many  hundreds  of  feet  below  the  sand  just  described. 

"Oil    Wells. 

"No  commercially  productive  wells  have  been  drilled  in  the  district,  but  several  pros- 
pect wells  have.  Among  these,  beginning  at  the  northwest,  are  the  R.  M.  Smith  well 
No.  1,  in  the  northeast  corner  of  Sec.  21,  T.  30  S.,  R.  20  E..  the  seven  wells  of  the 
R.  M.  Smith  Oil  Companv,  near  the  corner  stake  of  Sees.  22,  23,  26  and  27,  T.  30  S., 
R.  20  E.  ;  the  Cree  well,  in  tlie  southwest  corner  of  Sec.  22,  T.  31  S.,  R.  21  E.  ;  the 
Erume  test  holes  in  the  southern  part  of  the  same  section  ;  the  Schwartz  well  of  the 
Union  Company,  near  the  southeast  corner  of  Sec.  6,  T.  32  S.,  R.  22  E..  and  the 
Sperrv  or  Vi.slinu  well,  in  the  southeast  corner  of  Sec.   22,  T.  32  S.,  R.  22  E. 

"The  R.  M.  Smith  wells  in  Sees.  22.  23,  26  and  27.  T.  30  S.,  R.  20  E..  the  Erume 
wells  in  Sec.  22,  T.  31  S.,  R.  21  E.,  and  the  Vishnu  well,  in  Sec.  22.  T.  32  S.,  R.  22  E., 
have  yielded  traces  of  oil.  The  Smith  and  Erume  wells  are  shallow  and  have  yielded 
oil  only  in  small  quantities.  The  oil  is  of  a  good  quality,  and  is  said  to  test  about  2  8° 
Baume'  gravity,  although  occurring  witliin  less  than  100  feet  of  the  surface.  It  is 
brownish  to  greenish  in  color  and  has  very  little  viscosity.  It  is  said  that  this  oil  is 
used  in  its  native  condition  in  lamps,  making  a  somewhat  smoky  flame,  however. 
Nothing  definite  is  known  concerning  the  quality  of  the  oil  encountered  in  the  Sperry 
well,  but  it  is  said  to  have  been  of  very  good  quality  and  of  about  30°  Baume  gravity. 

"The  Carrizo  Plain  District  includes  the  region  southwest  of  Palo  Prieta  Pass  as 
far  as  the  southeast  corner  of  T.  28  S.,  R.  18  E.,  and  the  region  southwest  of  the 
crest  of  the  Diablo  Range  southeastward  from  the  same  corner.  It  embraces  the 
Carrizo  and   Elkhorn   plains,   the  northeastern   flank   of   the   Caliente   Mountains,   and 


PETROLEUM   RESOURCES   OF    CALIFORNIA.  101 

the  fringe  of  hills  along  the   southwestern   edge  of  the  Carrizo   Plain.     A  verjMiasty 
•Poonnnfssance   of  the   hills  southwest  of   the   Carrizo   Plain   as  far  south   as   Painted 
T^^^^k  RinA?  in  Soc    30    T    31  S     R.  20  E.,  discloses  evidence  of  petroleum  at  only  one 
?oiS      T^s'  ^"ts  in  ?he   northern  part  of  Sec.   23.   and  the  southern   part   of  Sec.   14 
T    ■  'V  «!     R    n  E     where  an  oil  sand  outcrops  at  the  base  of  the  Santa  Margarita  (  .) 
nn-mition      The    sand    here   was   not    over    10    feet    thick,    consisted   of   coarse   quar  z 
^  -V  ns   Tnd  showed  a  tendency  toward  concretionary  structure.     It  immediately  ovor- 
fiortheMontoieysirale    which  outcrops  in  the  axis  of  an  anticl  ne  passing  through 
t le  loc^l  trmentioned.     This  occurrence  of  oil  sand  indicates  that  petroleum  in  smal 
amolmis  occm's  at  the  base  of  the. Santa  Margarita  <  ?>   f";™=\\-"„f^'-°T9'^°"^lf  S'^ E 
a  Dortion  of  the  Carrizo  pla  n  region,  north  of  the  southern  pait  of   i.  -9  ^.,  k.  i»  l-. 
^°ItTs  not     bought  probable  that   deposits   of  economic   importance  will   ^'f   enco   n- 
tered  in  this  reg On    as  the  structural  conditions  are  more  or  less  unfavorable  o\y  ng 
to  The  numeroul   fan  ts   that   affect   the   formations  adjacent   to   the   phxin.     No   other 
ndiVUion^of   petro  eum   were   found   on    the  southwestern   flanks   of   Temblor   Range 
no  thoran  east-west  line  through  the  mouth  of  San  Diego  Canyon.     Numerou.s  ind  - 
ca  ions  of  petroleum  are  found  in   the   Vaqueros  and  overlying  formations  southoast 
of  sTn  D  ego  Camion,  along  the  flanks  of  the  Temblor  Range,  and  it  appears  h.glily 
provable  thTt  commercial  deposits  of  petroleum  occur  at  "^f 'Y  P'^-^^^f.^^^^^ft,  '^^f ^^^'n' 
clines    in    this   region.     The   anticline    ^yhich    begins    about   half   a   "^'^^    ^oj,'*^' j^^^and 
Diego    Joe's— that    is,    at    the    southeast    corner    of    Sec.    8.    T.    30    S      R.    t"    „  tp'^ed 
nasses  southeastward  along  the  flanks  of  the  range    (see  map,  II.   1)    bas  been  tested 
aftwo  different  localities  over  a  mile  apart,   at   the  Smith   wells  near  the  corner  of 
sL^    ■.•>    •>3    96  and  27.  T.  30  S..  R.   20   E.,  and  a  mile  northwest  of  that  point. 

"ThV'vac'lueroralso  yields  oil  near  the  surface  at  the  Erume  wells  in  the  ^''outhern 
mrt  of  Sec  ''^  T  31  S  R.  21  E.  The  peculiar  pinkish  color  indicative  of  petroleum 
fs  also  foi>nd"at  practically  all  the  outcrops  of  the  Vaqueros  in   the  anticlines  along 

^'''•'m-7ring  in'mind  Ihese  favorable  indications,  it  appears  probable  that  wells  .sunk 
thrnugh  tlie  overlving  M<.ntercy  .shale  and  tapping  tlic  Vaqueros  sand.stone  at  adv.  n- 
t  '-eoHs  localities  will  vield  petroleum.  As  the  petroleum  produced  by  the  shallow 
oles  so  far  sunk  is  particularly  good,  ranging  as  high  a.s  28'  Bav.me.  >t  f  ems  pro  1- 
able  that  oil  wherever  obtained  from  the  Vaqueros  will  be  excel  en  t.  As  tic  co  idi- 
Uonshei^>  mentioned  as  favorable  continue  practically  uninterrupti-d  along  the  range 
as7a  southeast  as  the  region  back  of  Sunset,  it  seems  likely  ^ha  pn.spec  ing  in 
f-ivorable  localities  in  the  Carrizo  Plain  District  should  secure  positive  i.-bull.s. 
oVing  o  the  complex  folding  and  accompanying  faulting  which  ^^^^^^^J;^'^^!^^}^!^- 
even  to  a  greater  extent  than  the  northeastern  flank  of  the  range,  detailed  examina- 
tions of  any  particular  area  should  be  made  before  predictions  arc  attempted.  On 
the  accompanying  map  (PI.  1)  the  principal  lines  of  structure  are  indicated  It  is 
thought  by  the  writers  that  the  anticlines  with  low-dipping  flanks  offer  the  best 
inducements   for   exploitation." 

The  area  of  the  Ciiyama  Valley  is  described  in  Chapter  IX  in  the 
article  on  Santa  Barbara  County. 


102  CALIFORNIA    STATE    MINING    BUREAU. 


CHAPTER  IX. 

Coast  Area  from  the  Santa  Maria  Rivlr  to  the  Santa  Monica 

Mountains. 

(Includes  the  counties  of  Santa  Barbara,  Ventura  and  Northwestern  Los  Angeles.) 
Santa   Barbara  County. 

The  principal  topograpliic  features  of  Santa  Barbara  County  consist 
of  the  San  Rafael  and  Santa  Ynez  ranges.  These  two  ranges,  starting 
from  a  common  point  on  the  east  line  of  the  county,  spread  out  fan-like 
to  the  west,  the  Santa  Ynez  group  running  due  east  and  west  along  the 
coast  line  and  the  San  Rafael  group  running  northwest  and  forming  the 
northern  boundary  of  the  county.  This  fan-like  arrangement  has 
resulted  in  an  area  of  about  twenty-four  miles  in  width  between  the  two 
ranges  in  the  western  portion  of  the  county  and  which  is  occupied  by  a 
series  of  low  hills  and  river  valleys. 

Beginning  on  the  north'flank  of  the  Santa  Ynez  and  going  north  to  the 
San  Rafael  Range,  these  hills  and  valleys  are  as  follows :  the  Santa  Ynez 
Valley;  the  Purisima  Hills;  tlie  Los  Alamos  and  San  Antonio  valleys; 
the  Solomon  and  Casmalia  hills  and  the  Santa  Maria  Valley. 

In  the  high  ranges  of  the  San  Rafael  and  Santa  Ynez  mountains,  the 
rocks  are  principally  of  Cretaceous  and  Eocene  age,  highly  folded  and 
crushed  and  with  little  or  no  oil  possibilities.  In  the  broad  depression 
in  the  western  portion  of  the  county  between  these  ranges,  there  have 
been  deposited,  great  tliicknesses  of  gently-folded  ^Miocene  and  Pliocene 
rocks  in  Avhicli  large  deposits  of  petroleum  have  formed  and  accumu- 
lated. This  entire  area  has  been  thoroughly  mapped  and  the  oil 
resources  reported  on  by  Arnold  and  Anderson.^ 

In  this  report  therefore  only  a  brief  description  of  the  fields  will  be 
given,  together  with  the  possibilities  of  their  extension  to  outlying  areas. 

Proven  Fields  and  Adjoining  Areas. 

Beginning  at  the  west  end  of  the  county,  the  first  proven  field  is  the 
Casmalia  Hills,  just  east  of  Schumann  Canyon  and  Casmalia  Station. 
The  structure  consists  of  the  broad  plunging  Schumann  antir-line,  wliich 
has  its  beginning  on  the  coast  between  Point  Sal  and  ]\Iussel  Rock  and 
runs  thence  southeast  along  the  ridge  of  the  Casmalia  Hills,  crossing 
Schumann  Canyon  about  one-half  mile  south  of  Schumann  Station  and 
continuing  southwest  down  the  canyon.  Avhere  the  principal  wells  are 
now  located,  and  finally  plunging  out  of  sight  at  a  point  on  the  state 
highway,  about  one  mile  south  of  Divide  Station. 

The  formations  exposed  consist  of  ^Monterey  shale  along  the  axis  of 
the  .'Hitv'^ipf,  and  on  the  north  flank  that  slopes  to  the  Santa  ]\Iaria 
Valley  the  i\Ionterey  is  overlaid  by  Fernando  sands  and  clays.  On  the 
south  flank  near  Casmalia  station  the  INIonterey  is  overlaid  by  recent 
terrace  deposits 

'U.  S.  Geological  Siirviy.  Bull.  .322.  Gtolosy  ami  Oil  Resources  of  the  Santa  Maria 
Oil  Distrift.  1907.      By  Ralph  Arnold  and  Robert  Anderson. 


PETROLEUM    RESOURCES   OP    CALIFORNIA.  103 

The  dips  on  the  flanks  of  the  folds  vary  from  8°  to  40°  in  the  area 
east  of  Schumann  Canyon  and  in  the  territory  to  the  west  they  run 
from  20°  to  80°.     The  phinge  to  the  southeast  averages  about  5°. 

Tlie  oil  originated  from  the  diatomaceous  shale  of  the  ^Monterey  and 
has  collected  in  the  hard,  flinty,  fractured  areas  of  the  shale.  The  field 
has  no  true  oil  sands. 

An  examination  of  the  IMonterey  shows  that  only  the  lower  half  is 
present,  the  upper  portion  liaving  been  removed  by  erosion.  The  large 
deposit  of  tar  and  the  burnt  shale  areas  in  the  hills  west  of  Schumann 
Canyon  probably  represent  the  basal  oil  measures  of  the  Monterey 
formation.  On  the  axis  of  tlie  fold  south  of  Waldorf,  the  Vaqueros 
sandstone  is  exposed.  East  of  Schumann  Canyon  the  plunge  of  the 
anticline  has  covered  the  oil  measures  with  a  thickness  of  about  1600 
feet  of  Monterey  shale,  which  acts  as  a  capping' for  the  oil. 

The  proven  areas  consist  of  approximately  1940  acres,  which  lie 
between  Casmalia  and  Schumann  Stations  and  east  of  the  Southern 
Pacific  Railroad.  In  December,  1920,  the  total  daily  production  from 
the  field  was  4517  barrels  of  oil.  The  average  number  of  wells  producing 
during  this  period  Mas  87  with  an  average  daily  production  per  well  of 
52  barrels  of  oil  and  150  of  water.  This  large  water  production  is  due 
to  the  failure  to  exclude  bottom  water  and  to  the  fact  that  the  lower  oil 
measures  contain  both  oil  and  water.  The  gravity  of  the  oil  varies  from 
9°  to  17°  Baume  in  the  western  portion  of  the  field,  but  increases  in 
gravity  to  the  soutlieast ;  wells  on  tlie  Escolle  lease  of  the  Union  show 
oil  as  high  as  25°  Baume.  Detailed  reports  on  the  underground  struc- 
ture and  the  water  conditions  may  be  found  in  the  annual  reports  of  the 
State  Oil  and  Gas  Supervisor.^ 

Drilling  has  shown  that  the  productive  area  on  the  north  flank  of  the 
anticline  is  about  1000  feet  in  width  and  on  the  south  flank  about  3000 
feet  in  width.  Efforts  to  extend  the  field  along  the  axis  of  the  fold  in 
the  hills  west  of  Schumann  Canyon  and  the  railroad  have  resulted  in 
failures,  this  being  due  to  the  fact  that  the  oil  measures  of  the  Monterey 
are  exposed  on  the  surface  in  this  area  and  contain  no  impervious  cap- 
ping. The  most  westerly  test  wells  were  drilled  by  the  Standard  Oil 
Company,  on  the  steeply  dipping  north  flank  of  the  Schumann  anticline 
southwest  of  "Waldorf  Station.  The  wells  failed  to  show  am^  oil  or  to 
penetrate  the  basal  bituminous  beds  of  the  Monterey,  which  outcrops  to 
the  south.  Outcrops  of  bituminous  sands,  probably  of  Vaqueros  age, 
are  exposed  on  the  axis  of  the  fold  south  of  the  above  mentioned  Standard 
wells  and  the  Vaqueros  may  possibly  contain  oil  in  this  area.  Wells 
to  test  these  sands  out  should  be  located  on  the  axis  of  the  fold  and  not  on 
the  steep  dipping  north  flank,  as  selected  by  the  Standard.  It  is  possible 
that  in  time  the  mining  and  distillation  of  the  bituminous  shales  of  this 
area  will  be  found  profitable. 

To  the  east  of  Schumann  Canyon  it  is  probable  that  the  field  may  be 
extended  beyond  the  present  southeast  limits  of  the  proven  area.  Recent 
drilling  .shows  that  this  extension  will  probably  continue  for  at  least  a 

'Second  Annual  Report   of  the  State  Oil  and  Gas  Supervisor,   pp.   204-207. 

Third  Annual  Report  of  the  Stat?  Oil  and  Gas  Supervisor,  pp.  .361-369,  372-384. 

Fifth  Annual  Report  of  the  State  Oil  and  Gas  Supervisor.      Summarv  of  Operations 
California  Oil    Fields,    April,    1920.     Report   on    the   Casmalia    Field.     By   H.    W.    Bell 
Pp.   10-4  0. 


104  CALIFORNIA    STATE   MINING   BUREAU. 

mile  along  the  axis  of  the  fold  southeast  of  Well  No.  13,  Escolle  Union  Oil 
Company. 

The  Santa  IMaria  field  proper,  known  as  the  "old  field,"  lies  to  the  east 
of  the  Casmalia  field  in  a  group  of  low  hills  known  as  the  Solomon  Hills. 

The  structure  consists  of  a  series  of  small,  sharply-folded  anticlines 
lying  to  the  south  and  west  of  ]\Iount  Solomon.  The  greater  part  of  the 
surface  of  the  field  is  covered  by  a  small  thickness  of  sands  and  clays 
of  the  Fernando  formation,  whicli  bear  no  relation  to  the  accumulation 
of  the  oil  and  serve  only  to  obscure  the  real  structure.  Beneath  the 
Fernando  is  found  the  Monterey  formation,  the  upper  portion  of 
which  outcrops  in  Pine  Canyon  and  on  the  Newlove  lease  of  the  Union 
Oil  Company.  At  both  of  these  localities,  the  ^Monterey  is  bituminous 
and  numerous  seepages  and  burnt  shale  areas  are  in  evidence.  The 
upper  portion  of  the  IMonterey  contains  what  is  known  as  the  '1st  zone,' 
which  is  productive  to  the  extent  of  about  ten  barrel  wells  in  certain 
portions  of  the  field.     The  oil  runs  in  gravity  from  16°  to  20°. 

Beneath  the  1st  oil  zone,  the  Monterey  is  composed  of  a  thickness  of 
about  1600  feet  of  blue  shale,  which  serves  as  an  impervious  capping 
for  the  2nd  oil  zone,  which  lies  at  the  base  of  the  INIonterey.  The  oil 
of  the  2nd  zone  has  collected  in  the  fractured  flinty  shale  that  makes  up 
this  portion  of  the  Monterey.  The  gravity  varies  from  20°  to  38°.  This 
zone  was  formerly  the  chief  source  of  production  in  the  field.  The  3rd 
zone,  now  the  chief  source  of  production,  is  probably  in  the  uppermost 
Vaqueros,  at  its  contact  with  the  Monterey.  The  oil  measures  in  this 
zone  are  true  sands.  Underground  contour  maps  indicate  that  this 
contact  between  the  IMouterey  and  the  oil  sand  of  the  Vaqueros  may  be 
a  fault  contact,  particularly  in  the  vicinity  of  the  Newlove  lease  of  the 
Union  Oil  Company.  Fig.  2,  Section  2,  shows  the  general  structure  of  the 
field. 

Detailed  reports  covering  the  underground  structure  and  water  con- 
ditions can  be  found  in  the  various  annual  reports  of  the  State  Oil  and 
Gas  Supervisor.^ 

The  total  proven  area  in  March,  1921,  was  4620  acres.  The  total 
daily  production  in  December,  1920,  was  8006  barrels  of  oil.  The  aver- 
age number  of  wells  producing  during  this  month  was  232,  with  an 
average  daily  production  per  well  of  34.5  barrels  of  oil  and  29.5  barrels 
of  water.  The  limits  of  the  field  have  been  defined  by  past  drilling  and 
there  will  probably  be  no  appreciable  extension  of  these  limits.  There, 
however,  remain  extensive  areas,  particularly  in  the  western  portion  of 
the  field,  that  have  not  been  drilled  up  to  date. 

The  Cat  Canyon  field  lies  along  the  canyon  of  that  name,  north  and 
east  of  the  Santa  Maria  field.  The  formations  exposed  on  the  surface 
consist  of  terrace  deposits  and  Fernando  sancLs  and  clays.  The  total 
thickness  of  the  terrace  deposits  is  about  fifty  feet  and  the  Fernando 
outcrops  from  600  to  800  feet.  The  Monterey  shale  is  present  beneath 
the  Fernando  and  it  is  both  the  source  and  reservoir  for  the  oil,  whicli 
averages  about  15°  in  gravity. 

The  structure,  according  to  Arnold  and  Anderson,^  consists  of  two 
parallel  anticlines,  about  two  miles  apart,  with  a  northwest-southeast 

'Firstt  Annual  Report  of  the  State  Oil  and  Gas  Supervisor,  pp.  19S-203,  205-211. 
Second  Annual  Report  of  the  State  Oil  and  Gas  Supervisor,  pp.  202-204. 
Third  Annual  Report  of  the  State  Oil  nnd  Gas  Supervisor,  pp.  370-371. 
=U.  S.  Geological  Survev.     Bull.  322.     Geology  and  Oil  Resources  of  the  Santa  Maria 
Oil  District.     By  R,  Arnold  and  R.  Anderson,  1907. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  105 

trend.  The  most  .soiitlicrly  fold,  known  as  llie  Gate  Ridge  anticline, 
according  to  surface  dips  runs  along  the  top  of  the  ridge  on  the  south 
side  of  Canada  del  Gato.  Drilling,  however,  has  shown  that  the  actual 
productive  fold  in  the  underlying  iMonterey  lies  about  one  mile  north 
of  where  Arnold  and  Anderson  located  the  axis,  from  dips  in  the  Fer- 
nando. The  axis,  as  determined  by  drilling,  apparently  runs  through 
Palmer  Union  No.  1  in  Sec.  26,  T.  9  N..  R.  33  W.,  S.  B.  M.,  and  thence 
southeast,  passins:  near  the  location  of  the  Associated  Oil  Company's 
well.  Recruit  No.  1,  oh  Sec.  31,  T.  9  N.,  R.  32  W.,  and  from  there  con- 
tinuing southeast  to  the  head  of  Howard  Canyon.  The  principal 
area  of  production  lies  at  the  northwest  end  of  this  fold  in  Sec.  26.  The 
Bell  wells  of  tlio  Pan-American  Company,  located  on  the  Bell  Ranch  and 
on  the  axis  of  the  fold,  a.s  shown  by  Arnold  and  Anderson,  have  failed 
to  produce  any  appreciable  amount  of  oil  and  the  majority  of  them 
have  been  abandoned.  The  second  anticline  runs  along  the  ridge  mark- 
ing the  north  side  of  Caiiada  del  Gato  and  its  location  on  the  surface  in 
the  Fernando  beds  is  slightly  north  of  its  location  in  the  underl3'ing 
Monterey.  The  principal  area  of  production  on  this  fold  centers  around 
Sec.  30,  T.  9  N..  R.  32  W.,  S.  B.  M.  The  oil  measures  in  the  Cat  Canyon 
field  are  true  sands  and  probably  represent  sandstone  beds  in  the  middle 
]\lonterey.  The  wells  vary  in  depth  from  24G0  to  3100,  according  to 
their  position  on  the  fold.  The  total  area  of  proven  land  in  March,  1921, 
was  approximately  1850  acres.  The  total  daily  production  in  December, 
1920.  was  2333  barrels  of  oil.  The  average  numl)er  of  producing  wells 
during  this  period  was  40,  with  a  daily  average  production  per  well  of 
56.3  barrels  of  oil  and  8  of  water.  It  is  probable  that  the  limits  of  the 
proven  areas  may  be  extended  to  the  southeast  along  the  axes  of  both 
folds.  Detailed  reports  on  the  underground  structure  may  be  found  in 
the  annual  reports  of  the  State  Oil  and  Gas  Supervisor.^ 

The  Purisima  Hills  field  lies  to  the  south  of  the  proven  area  above 
described.  That  portion  of  the  field  which  may  be  considered  as  proven 
occupies  the  western  end  of  the  Purisima  Hills,  in  the  vicinity  of  the 
Lompoc  grade,  and  the  area  has  been  frequently  called  the  Lompoc  field. 

The  dominant  structure  of  this  region  is  a  broad  anticline  running 
west  from  Red  Rock  IMountain  to  the  Lompoc  Grade,  where  it  disap- 
pears under  the  terrace  deposits  of  Burton  ]\lesa.  At  the  west  end, 
near  the  Hill  wells  of  the  Union  Oil  Company,  the  south  flank  of  the  fold 
is  faulted.  This  fault  appears  to  have  influenced  the  accumulation  of 
the  oil,  as  the  wells  in  the  vicinity  of  the  fault  zone  have  been  the  best 
producers.  The  formations  consist  of  the  Fernando  and  the  Monterey, 
the  latter  being  both  the  source  and  reservoir  for  the  oil. 

The  total  proven  area  in  March,  1921,  was  1193  acres.  The  total  daily 
production  in  December,  1920,  was  1367  barrels  of  oil.  The  average 
number  of  wells  producing  during  this  period  was  27,  with  an  average 
daily  production  per  well  of  50  barrels  of  oil  and  70  of  water. 

Surface  geologs^  indicates  that  the  field  may  possibly  be  extended. 
That  portion  of  the  Purisima  Hills  between  the  Lompoc  field  and  Red 
Rock  ^lountain.  a  distance  of  approximately  ten  miles,  may  be  considered 
as  possible  oil  territory.     The  most  favorable  localities  would  be  along 

"First  Annual  Report   Slate  Oil  and  Gas  Supervisor,   pp.   203-204. 
SeconcJ  Annual  Report  of  the  State  Oil  and  Gas  Supervisor,  pp.  210-219. 


106  CALIFORNIA    STATE    MINING   BUREAU. 

the  axis  of  the  anticline  above  mentioned  and  along  an  eastward  continu- 
ation of  tlie  fault  zone  noted.  There  are  large  deposits  of  asphaltum 
in  the  Monterey  near  Red  Rock  IMcuntain,  indicating  that  the  INIonterey 
carries  petroleum  in  the  eastern  end  of  the  Hills.  The  possibility  of 
finding  production  in  commercial  quantities  depends  on  the  presence  of 
the  thick  blue  shale  zone,  which  acts  as  a  capping  for  the  2nd  and  3rd 
oil  zones  of  the  Santa  Maria  field.  If  this  blue  shale  is  present  in  tlie 
rurisima  Tlills,  overlying  the  fractured  flinty  ])ituminous  shale  zone  as 
exposed  in  the  vicinity  of  Red  Rock  Mountain,  then  the  possibility  of  a 
large  area  in  the  eastern  portion  being  productive  is  good. 

Five  wells  are  now  being  drilled  to  test  out  this  area.  Harris  No.  1 
and  Careaga  No.  87  of  the  Western  Union  Company  are  located  on 
the  axis  of  the  anticline  about  one  mile  east  of  the  proven  area.  Pinal 
Dome  No.  1  is  located  on  the  eastern  extension  of  the  fault  zone  and  has 
apparently  the  best  chance.  At  the  eastward  end  of  the  Hills,  the  Gen- 
eral Petroleum  Corporation  is  drilling  a  well  in  Drum  Canyon  on  the 
axis  of  the  fold  and  about  two  miles  farther  east,  near  Red  Rock  ]\Ioun- 
tain,  the  Standard  Oil  Company  is  drilling  a  well. 

The  territory  west  of  the  Lompoc  field  is  known  as  Burton  IMesa.  The 
surface  formation  is  mainly  terrace  deposits,  with  some  underlying 
INIonterey  exposed  in  the  canyons.  On  account  of  the  overlying  terrace 
deposits  the  true  structure  of  the  region  is  obscure.  Wherever  the  IMon- 
terey  is  exposed  it  apparently  is  folded  into  a  number  of  small  anticlines. 
At  the  western  end  of  the  Mesa,  along  the  coast  line,  hard  flinty  Monterey 
shale  with  numerous  seepages  is  exposed.  The  area  might  be  considered 
as  worthy  of  further  investigation. 

Outlying  Areas. 

The  general  area  of  the  Santa  Ynez  Mountains  west  of  the  town  of 
Santa  Barbara  offers  no  inducement  for  drilling.  The  core  of  the  range 
is  composed  mainly  of  Eocene  and  Oligocene  sandstones  and  Vaqueros 
sandstone.  Along  the  edge  of  the  Santa  Ynez  Valley  there  are  small 
areas  of  highly-folded  Monterey  shale,  and  along  the  coast  there  is  a  very 
small  thickness  of  Monterey  shale  exposed  along  the  sea  cliffs,  overlying 
the  Vaqueros  sandstone  and  dipping  about  40°  to  the  south.  The  Mon- 
terey here  is  slightly  bituminous  in  places.  The  general  structure  of 
the  range  is  that  of  a  great  monocline,  which  dips  from  the  high  central 
ridge  at  an  angle  of  about  45°  to  the  south. 

The  San  Rafael  Range  is  composed  mainly  of  Cretaceous  and  Eocene 
sediments,  all  highly  folded  and  containing  no  evidence  of  petroleum. 
On  the  south  flank,  north  of  the  Santa  INIaria  Valley,  there  is  a  large 
area  of  highly-folded  Monterey  shale,  probably  representing  the  lower 
portion  of  this  formation.  In  the  southeastern  portion  of  this  area, 
l)etween  Foxen  Canyon  and  Sisquoc  River,  the  JMonterey  is  overlaid  by 
thin  patches  of  Fernando,  at  the  contact  of  which  there  are  large  deposits 
of  asphaltum  as  well  as  in  the  shale  itself.  The  asphaltum  deposits  are 
located  along  Asphaltum  Creek  and  Zaca  Creek  and  on  Labrea  Creek, 
north  of  the  Sisquoc  River.  The  territory  is  not  favorable  for  well 
drilling,  but  offers  a  possibility  of  mining  and  distilling  the  bituminous 
deposits.  In  the  hills  due  north  from  Los  Olivos,  the  Fernando  is 
exposed  in  a  broad  anticline,  which  has  been  tested  by  the  Standard  Oil 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  107 

Company,  in  two  wells.  No  oil  was  encountered  and  the  drilling  demon- 
strated what  is  evident  from  a  study  of  the  territory  to  the  north,  that  is, 
the  Monterey  is  missing  on  this  fold,  the  wells  penetrating  Franciscan 
serpentine  after  going  through  llie  Fernando. 

In  prospecting  for  oil  in  tiie  Santa  ^laria  district  the  following  facts 
must  be  borne  in  mind:  (1)  All  production  is  in  the  lower  portion  of 
the  ^Monterey  and  in  one  instance  in  the  uppermost  Vaqucros.  (2)  Com- 
mercial production  is  oidy  found  when  tlie  lower  flinty  productive  zone 
of  the  IMonterey  is  capped  by  the  impervious  blue  shale  l3ody.  (3)  The 
Fernando  is  not  productive,  nor  do  folds  in  the  Fernando  reflect  the 
structure  in  the  underlying  Monterey. 

Area  of  the  Cuyama  Valley. 

Tlie  Cuyama  Valh-y  lies  along  the  nortii  flank  of  the  San  Kafael 
Mountains,  which  locally  are  sometimes  known  as  the  Cuyama  IMountains. 
Along  its  western  portion  the  valley  forms  the  dividing  line  between 
Santa  Barbara  and  San  Luis  O])isi)o  counties.  The  extreme  eastern 
portion  lies  in  Ventura  County.  The  geology  and  oil  resources  of  the 
major  ])ortion  of  the  valley  luive  been  reported  on  by  the  United  States 
Geological  Survey^  and  the  conclusion  of  English's  report  is  as  follows: 

"Conditions    in    Cuyama    Valley. 

"As  thf  association  of  sandy  beds  witli  tlie  shale  which  was  the  original  source 
of  the  oil  is  one  of  the  most  inipoi'tant  conditions  in  productive  fields,  the  discussion 
of  the  Cu\ama  N'alley  area  will  he  based  on  the  areal  distribution  and  character  of 
such  shale.  The  shales  present  in  the  Cuyama  Valley  are  the  thick  mass  of  pre- 
Monterey  shale,  tlie  shale  in  the  Vaqueros  formation,  the  Maricopa  shale,  and  the 
locally  well-developed  Whiterock  Bluff  shale  member  of  the  Santa  Margarita  for- 
mation. 

"There  appears  to  be  little  possibility  of  obtaining  oil  from  beds  associated  with 
the  dark  clay  shale  of  the  pre-Monterey  rocks,  which  crops  out  over  considerable 
areas  in  the  rugged  mountains  on  the  south  side  and  in  the  western  part  of  the 
Cuyama  Valley.  Lithologically  similar  shale  of  Cretaceous  age  on  the  west  side  cf 
the  Sacramento  Valley  contains  oil  seeps,  and  in  the  Santa  Clara  River  valley  some 
of  the  oil  probably  originated  in  the  Topatopa  (Eocene)  shale,  which  is  of  much  the 
same  type  and  possibly  of  tlie  same  age  as  the  shale  of  the  pre-Monterey  in  this  area. 
However,  in  the  area  examined  no  seeps  or  other  evidence  of  the  presence  of  oil 
were  found  or  were  reported  in  this  shale,  or  in  overlying  beds,  so  that  it  seems 
unlikely  that  any  appreciable  amount  of  oil  derived  from  it  is  present  either  in  the 
interbedded  sandstones  or  in  porous  overlying  formations.  Much  the  same  reasoning 
may  be  applied  to  the  dark  clay  shale  and  interbedded  sandstone  of  the  Vaqueros 
formation,  which   constitutes  the   main   mass  of  the   Calienle  Range. 

"Of  the  other  formations,  the  pearl-giay  shale  in  the  vicinity  of  Montgomery 
Potrero,  the  pinkish  Maricopa  shale  on  the  flanks  of  the  Caliente  Riinge,  and  the 
"chalky"  Whiterock  Bluff  shale  member  of  the  Santa  Margarita  are  the  only  beds 
that  are  of  a  lithologic  type  in  which  it  seems  likely  that  oil  may  have  originated, 
and  only  those  general  areas  in  which  one  of  thesa' shales  crops  out  or  is  believed 
to  be  pre.sent  lielow  the  surface  are  thouglit  to  be  likely  to  produce  oil. 

"The  gi'ay  diatomaceous  shale  which  is  mapped  as  a  part  of  the  Pato  red  member 
of  the  A'aqueros  and  which  underlies  the  prominent  white  sandstone  of  the  Vaqueros 
at  Montgomery  Potrero  has  a  very  irregular  distribution,  being  absent  along  the 
Monterey  and  pre-Monterey  contact  west  of  Branch  Canyon  and  on  the  south  side 
of  the  tilted  block  of  pre-Monterey  rocks  at  the  head  of  Castro  Canyon.  It  probably 
underlies  the  western  part  of  the  prominent  anticline  north  of  Salisbury  Potrero, 
but  its  slight  thickness  and  meager  content  of  diatomaceous  material  make  it 
insignificant  in  comparison  with  the  great  mass  of  diatomaceous  shale  in  productive 
fields.  No  seeps  arc  known  to  occur  in  this  shale  or  in  associated  porous  rocks.  The 
chance  of  obtaining  commercial  fiuantiti'es  of  oil  from  beds  overlying  this  shale  in 
the  area  mapped   is  therefore  probably  slight. 

"The  Maricopa  shale,  in  the  uprier  part  of  the  Monterey  group  of  the  Calienle 
Range,  has  a  maximum  thickness  of  about  2000  feet,  and  although  less  diatomaceous 
than  the  typical  "Monterey  shale,"  it  may  have  been  the  source  of  considerable  quan- 
tities of  petroleum.     Two  or  three  oil  seeps  have  been  reported  in  this  shale. 

'U.  S.  Geological  Survey.  Bull.  621-M.  Geology  and  Oil  Prospects  of  the  Cuvama 
Valley.     By  W.  A.  English,  1916. 


108  CALIFORNIA    STATE    MINING   BUREAU. 

"The  white  diatomaceous  shale  in  the  Whiteroek  Bluff  shale  member  is  locally 
over  10  00  feet  thick  and  may  have  been  the  source  of  considerable  quantities  of  oil. 
It  is  significant  that  the  seep  south  of  Whiteroek  Bluff  occurs  at  a  point  where  this 
shale  is  thickest  as  well  as  most  diatomaceous.  Areas  of  favorable  structure  under- 
lain by  eitlier  this  or  the  Maricopa  shale  would  deserve  very  careful  consideration 
as  being  possibly  productive.  Unfortunately  no  such  areas  of  favoi-able  structure 
were   found. 

"The  structure  in  tlie  Caliente  Range  is  unfavoraljle  for  the  collection  of  oil  from 
eitlier  of  these  formations,  as  they  are  overlain  by  porous  beds  only  on  the  Hanks  of 
the  anticline,  where  the  beds  stand  nearly  on  edge.  The  Whiteroek  Bluff"  shale 
member  of  the  Santa  Margarita  west  of  the  fault  that  trends  northwest  from  the 
mouth  of  Morales  Canyon  is  thin  but  very  diatomaceous.  However,  the  broad 
syncline  in  which  it  lies  is  not  a  favorable  structure  for  the  accumulation  of  oil. 

"Between  Whiteroek  Bluff  and  the  outcrop  of  the  Santa  Margarita  formation, 
west  of  Salisbury  Canyon,  and  northward  to  Cuyama  River  is  an  area  in  which  a 
determination  of  either  the  structure  or  the  distribution  of  the  formations  that  may 
have  been  a  source  of  oil  is  uncertain  because  of  the  presence  over  most  of  the 
surface  of  the  Cuyama  formation  and  terrace  gravels.  As  the  underlying  structure 
is  unknown  this  area  cannot  be  classed  as  definitely  barren  of  oil.  although  there 
is  no  positive  evidence  to  i-ecommend  it  as  an  area  favorable  for  oil  accumulation. 
The  small  area  of  pre-Monterey  rocks  overlain  by  the  Morales  member  of  the  Santa 
Margarita  south  of  Whiteroek  Bluff  is  important  as  showing  that  the  diatomaceous 
shale  does  not  extend  directly  south  from  Whiteroek  Bluff  to  the  edge  of  the  valley. 
In  the  absence  of  more  definite  evidence  it  may  be  assumed  that  the  diatomaceous 
shale  is  absent  south  of  a  line  drawn  from  the  small  area  mentioned  to  the  point 
where  Aliso  Canyon  enters  the  main  body  of  pre-Monterey  rocks.  Northeast  of  that 
line  the  Cuyama  River,  and  the  Whiteroek  Bluff  shale  between  Salisbury  and  Aliso 
canyons  is  less  diatomaceous  than  at  Whiteroek  Bluff.  If  one  may  judge  of  the 
amount  of  oil  formed  in  the  slxxle  by  its  thickness  and  the  amount  of  diatom  skeletons 
pi-esent  in  it,  then  only  a  comparatively  small  quantity  of  oil  should  be  e.vpected  to 
occur  in  this  area.  Any  oil  which  may  have  originated  in  these  shales  might  have 
collected  either  in  interbedded  sandstones  or  at  the  base  of  the  Cuyama  formation, 
having  seeped  up  from  the  eroded  edge  of  the  underlying  shale.  A  well  of  compara- 
tively shallow  depth  located  on  any  one  of  a  number  of  low  local  anticlines  in  tiie 
Cuyama  formation  would  test  the  sands  at  the  base  of  that  formation,  as  the  Cuyama 
formation  in  this  area  is  probably  not  over  200  or  300  feet  thick.  This  thickness 
of  beds  would  probably  not  give  sufficient  covering  to  retain  any  large  quantity  of 
oil,  and  the  very  marked  unconformity  between  the  Santa  Margarita  and  Cuyama 
formations  suggests  that  a  large  part  of  the  oil  might  have  escaped  from  the  lower 
beds  before  the  overlying  beds  were  deposited,  so  that  on  the  whole  the  prospect  of 
obtaining  more  than  small  quantities  of  oil,  if  any,  in  this  area  is  not  promising. 

"Oil  Seeps. 

"The  largest  seep  reported,  and  the  only  one  seen  by  the  writer,  occurs  in  the  bed 
of  the  Cuyama  River  south  of  Whiteroek  Bluff.  The  river  has  cut  down  about 
twenty  feet  through  Quaternary  stream  deposits  and  is  fiowing  on  bedrock,  here 
diatomaceous  shale  of  the  Whiteroek  Bluff  member  of  the  Santa  Margarita.  During 
an  earlier  epoch  the  river  cut  down  to  the  same  level  and  formed  a  much  wider 
valley  in  which  the  stream  gravel  and  sand  that  form  the  vertical  banks  of  the 
present  stream  were  deposited.  It  was  during  this  earlier  epoch  in  which  the  river 
flowed  upon  bedrock  that  most  of  the  oil  now  seen  at  this  locality  seeped  up  from  the 
underlying  shale  of  the  Santa  Margarita.  While  tlie  river  was  flowing  on  bedrock 
and  while  it  was  depositing  three  or  four  feet  of  sand  a  number  of  pools  of  oil  were 
formed  here,  some  not  less  than  100  yards  across.  The  oil  in  these  pools  saturated 
the  surface  sand,  which  was  later  covered  by  sediment  and  preserved  and  which  is 
now  traceable  along  the  vertical  river  banks  as  thin  strata  of  oil  sand  interbedded 
with  white  sand  and  clay.  At  one  place,  which  may  have  been  the  original  seep, 
an  asphalt-like  oil  has  escaped  from  the  underlying  shale  very  recently.  The  shale 
near  this  seep  has  irregular  dips  and  the  oil  may  have  come  up  along  or  close  to  a 
fault. 

"At  least  three  seeps  of  oil  are  reported  in  areas  of  Maricopa  shale  of  the  Mon- 
terey group  in  the  Caliente  Range,  but  at  the  time  of  the  writer's  visit,  they  could 
not  be  located  and  had  probablv  ceased  to  How.  A  reported  seep  in  a  small  canyon 
in  the  NW.  \  Sec.  15.  T.  11  N.,  R.  2S  W..  could  not  be  found.  There  is  said  to  be 
a  snuill  hrea  deposit  on  a  ridge  in  the  SE.  \  Sec.  14,  T.  11  N.,  R.  28  W.  A  seep 
reported  in  the  creek  bed  near  the  forks  of  Taylor  Canyon,  in  the  SE.  J  Sec.  24, 
T.   32   S.,   R.   19    E.,   has  also  apparently   ceased  to  exist. 

"Wells  Drilled  for  Oil. 

"The  Webfoot  well,  in  a  nairow  gulch  on  the  north  side  of  Ballinger  Canyon,  in 
the  SE.  5  Sec.  2,  T.  9  N.,  R.  2  4  W.,  was  started  about  1905,  and  drilling  continued 
intermittently  for  a  number  of  years.  It  is  said  to  have  reached  a  depth  of  ISOO 
feet  without  encountering  any  oil.  This  well  starts  in  nearly  vertical  beds  of  brown 
sandy  shale  of  the  Monterey  group. 

"The  Grand  Prize  Oil  Company,  composed  of  Bakersfield  and  local  people,  drilled 
a  well  in  Sec.  G,  T.  11  N..  R.  28  W.,  at  about  the  same  lime  as  the  Webfoot  well  was 
drilled.     This  well  is  said  to  have  reached  a  depth  of  600  or  700  feet  without  obtaining 


PETROT>EUM    RESOURCES   OF    CALIFORNIA.  100 

any  oil.  It  starts  in  tho  "chalky"  white  shale  of  tlie  Whiterock  Bluff  shale  member 
of  the  Santa  Margarita  ami  probably  reaches  the  underlying  pre-Monterey  rock.  It 
is  located   on   the   south   Hank  of  a   broad  syncline." 

It  is  apparent  from  the  above  report  that  the  possil)ility  of  any  appre- 
ciable production  of  oil  in  the  Cuyania  Valley  is  slight. 

Coast  Area  of  Santa  Barbara  County. 

The  only  other  area  in  the  county,  outside  of  the  Santa  ]\Iaria  District, 
that  contains  any  oil  pos.sil)ilities  is  tho  narrow  coastal  strip,  from 
Goleta  to  tlie  Ventura  County  line.  The  territory  contains  one  small 
proven  district,  namely  the  Summerland  field,  located  about  eight 
miles  east  of  Santa  Barbara.  There  are  possiblities,  however,  that  other 
similar  fields  may  be  developed  in  this  area. 

The  coastal  strip,  with  an  average  width  of  almost  five  miles,  lies 
between  the  rugged,  steep  Santa  Ynez  Range  and  the  Pacific  Ocean.  The 
Santa  Ynez  Range  at  this  point  is  composed  of  highly-tilted  rocks  of 
Eocene  and  Oligoeene  age,  corresponding  to  the  Topatopa  and  Sespe 
formations  of  Ventura  County.  The  organic  shales  of  the  Topatopa 
have  been  the  source  of  some  oil  which  has  collected  in  beds  along  the 
contact  with  the  Sespe.  In  the  area  under  discussion,  this  condition 
exists  in  the  foothill  area  of  the  Santa  Ynez,  east  of  Summerland,  in  Tore, 
Oil  and  Santa  ^Monica  canyons 

Along  the  coastal  strip,  the  oil  is  found  in  the  Fernando  sandstone, 
having  accumulated  there  from  the  underlying  Monterey.  This  is  the 
condition  that  exists  in  the  Summerland  field,  the  .structure  of  which 
is  a  steep  monocline  in  the  underlying  ^Monterey  with  small  minor  folds 
in  the  overlying  Fernando.  The  field  is  located  along  the  water's  edge 
and  the  majority  of  the  wells  are  drilled  from  wharves  extending  out 
into  the  sea.  The  depths  range  from  100  to  600  feet  and  the  gravity 
from  14°  to  16°  Baume. 

In  December,  1920,  the  total  number  of  wells  producing  was  120. 
The  average  production  per  day  per  well  was  1.4  barrels  of  oil  and  14.2 
barrels  of  water.  The  total  daily  production  from  the  entire  field  was 
168  barrels  of  oil. 

The  most  favorable  location  for  new  fields  in  the  coastal  area  would  be 
where  the  Fernando  is  folded  in  anticlines,  overlying  the  IMonterey. 
Two  such  areas  are  apparently  present;  one  lying  in  the  hills  between 
Santa  Barl)ara  and  Goleta  and  the  second  between  Santa  Barbara  and 
IM'ontecito.  In  the  first  area  a  well  was  drilled  some  years  ago  on  the 
Hope  Ranch  by  the  Associated  Oil  Company,  called  the  Recruit  well. 
A  depth  of  2800  feet  was  reached  and  considerable  gas  was  encountered. 

The  foothills  of  the  Santa  Ynez  ^lountains,  northeast  of  Sununerland. 
in  the  vicinity  of  Toro  and  Santa  ^lonica,  offer  a  possibility  of  small 
production  of  Eocene  oil. 

At  Rincon  there  are  some  shallow  wells  which  have  obtained  slight 
showings.  The  region  between  Santa  Barbara  and  Carpinteria,  includ- 
ing the  Summerland  field,  has  been  reported  in  detail  by  the  United 
States  Geological  Survey.^. 

'U.  S.  Geological  Survey.  Bull  321.  Geology  and  Oil  of  the  Summerland  District. 
By  R.  Arnold,  1907. 


no  CALIFORNIA    STATE    MINrSTG   BURKAU. 

Fnllo\viii,2r  is  a  portion  of  the  report  refjardiug  the  old  wells  in  the 
outlying  areas  aud  future  possibilities  of  these  areas: 

"Wells    Near    Loon    Point. 

"Several  prospect  wells  have  been  put  clown  in  the  Fernando  formation  near  Loon 
Foint,  about  a  mile  east  of  the  Summerland  field,  but  none  were  successful,  although 
oil  sands  with  traces  of  oil  were  penetrated  in  most  of  them  It  is  the  opinion  of  the 
writer  that  the  paucity  of  petroleum  is  due  to  the  position  of  tlie  Fernando  beds,  which 
are  believed  to  overlie  here  the  nonbituminous  Vaqueros  rather  than  the  petroliferous 
Monterey  as  they  do  farther  north  in  the  Summerland  field.  The  position  of  the  Loon 
Point  wells  relative  to  tlie  anticline  is  apparently  advantageous  and  the  only  reason 
that   can   be   assigned   for   their   nonproductiveness   is   that   stated   above. 

"Wells    Near    Carplnteria    and    Rincon    Creek. 

"Several  wells,  at  least  one  attaining  a  depth  of  over  3000  feet,  have  been  sunk  on 
the  lowlands  in  the  region  near  Carplnteria  and  the  mouth  of  Rincon  Creek,  five  to 
eight  miles  east  of  Summerland.  Traces  of  oil  were  found  in  all  of  them,  but  none  so 
far  have  been  highly  successful.  In  all  the  wells  the  strata  penetrated  beneath  the 
superficial  Pleistocene  deposits  have  been  the  Monterey  (middle  Miocene)  bituminous 
shale,    which  lies   in   steeply   dipping  positions  throughout   this   coastal   belt. 

"The  most  important  and  deepest  well  is  tliat  of  the  Columbia  Oil  and  Asphalt  Com- 
pany, located  on  tlie  north  side  of  the  railroad  one-half  mile  east  of  the  asphalt  mine 
ai  Carplnteria.  It  is  put  down  in  line  with  the  axis  of  a  sharp  auticline  which  extends 
into  the  ocean  about  a  mile  east  of  the  mouth  of  Carplnteria  Creek,  near  the  edge  of 
the  area  shown  on  tlie  map.  No  definite  information  concerning  the  well  was  obtainable 
at  the  time  of  tlie  writer's  visit  (October.  1906).  but  the  following  notes  were  gleaned 
from  various  sources :  The  weil  penetrates  shale  throughout  the  greater  part  of  its 
depth,  is  about  3000  feet  deep,  and  encounters  artesian  water  with  a  head  of  12  feet 
at  100  to  150  feet,  asphaltum  at  1200  to  1400  feet,  and  oil  in  sandy  layers  in  the  lower 
100  feet.  The  oil  in  the  sump  is  black  and  heavy,  although  it  is  said  by  the  operators 
that  oil  of  37°  gravity  was  struck  near  the  bottom.  The  oil  is  accompanied  by  a 
strong  gas  pressure.  Gas  was  also  encountered  with  the  asphaltum  between  1200  and 
1400  feet,  forcing  the  asphaltum  up  in  tlie  hole  for  a  distance  of  ISO  feet  when  first 
struck.  Only  a  small  amount  of  oil  was  on  the  sump,  indicating  that  the  production, 
of  the  well  is  probably  not  large. 

"Several  years  ago  a  well  was  sunk  in  the  shale  at  the  edge  of  the  bluff  about  one- 
fourth  mile  east  of  the  asphalt  mine.  Heavy  oil  was  struck,  but  it  was  too  vi-scous 
for  pumping,  and  the  well  was  abandoned.  The  casing  of  this  hole  still  protrudes 
from  the  ground,  and  a  heavy  oil,  accompanied  by  considerable  gas,  is  slowly  escaping 
from  it.  It  is  said  that  a  second  well  was  simk  a  short  distance  farther  northeast, 
but  that  no  oil  of  consequence  was  encountered  in  it.  As  the  first  well  is  near  the 
northern  limit  of  a  highly  disturbed  zone,  it  seems  very  likely  that  the  reason  no 
oil  was  encountered  in  the  second  well  was  because  it  penetrated  beds  which  were  so 
little  fractured  that  the  oil   had  no  channels  of  migration  through  them. 

"In  1894  a  4  by  6  foot  well  was  dug  to  a  depth  of  3.^4  feet  by  P.  C.  Higgins,  on  the 
seashore  one-half  mile  west  of  the  asphalt  mine.  Purplisli  bituminous  shale,  with  casts 
of  the  fossil  Pecten  peckhami  Gabb,  was  the  only  formation  penetrated,  and  no  oil 
was  encountered. 

"A  400-foot  well  was  drilled  by  J.  Heath  on  the  Hill  ranch  just  north  of  the  mouth 
of  Rincon  Creek,  oil  being  struck  in  small  quantities  from  1.50  feet  downward. 

"Watts«  gives  tlie  following  reference  to  prospect  wells  of  the  Arctic  Oil  Company, 
east  of  Carplnteria : 

"'Well  No.  1.  sevpn  miles  south  of  Rincon  Creek.  1825  feet  deep:  formation,  red 
sandstone;  no  oii.  ^yell  No.  2,  50  feet  distant  from  Well  No.  1,  2100  feet  deep;  forma- 
tion, red  sandstone;  no  oil.  Well  No.  3,  on  Southern  Pacific  Railroad,  IJ  miles  east  of 
Carplnteria;  conglomerate  and  sandy  shale  to  700  feet;  shale  and  sandstone  to  1200 
feet :  liquid  asplialtum  ;  well  abandoned.' 

"The  conglomerate  here  mentioned  is  probably  the  Pleistocene  gravel  and  sand, 
which  overlies  the  Monterey  shale  to  a  depth  of  over  a  hundred  feet  in  the  region 
northeast  of  Carplnteria. 

"At  the  time  of  the  writer's  visit  to  Carplnteria  (October,  1906),  it  was  reported 
that  a  well  was  being  sunk  at  Shepards,  two  miles  northeast  of  the  mouth  of  Rincon 
Creek,  but  no  data  concerning  its  depth  or  the  formation  penetrated  were  obtainable. 

"Wells  in  the   Mountains   Northeast  of  Summerland. 

"Several  wells  have  at  different  times  been  put  down  in  the  Topatopa  formation 
(Eocene)  in  the  mountains  east  and  northeast  of  Summerland.  The  wells  have'all 
been  located  near  oil  springs  or  seepages,  and  have  without  exception  yielded  traces 
and  some  of  them  commercial  quantities  of  oil.  Light  yields  and  lack  of  proper  trans- 
portation and  market  facilities  have  discouraged  development,  and  at  the  present  time 
none  of  the  wels  ar^  being  operated.  .Among  the  wells  are  tho.«e  of  the  .^anta  Barbara 
Oil  Company  in  Oil  Canyon,  the  Occidental  Mining  and  Petroleum  Company  in  Toro 
Canyon,  the  Santa  Monica  Oil  Company  in  Santa  Monica  Canyon,  and  the  Pinal  Oil 
Company  at   tlie  moutli   of  Arroyo  Parida.      These  will  be  briefly  described. 

"Two  wells  were  drilled  by  the  Santa  Barbara  Oil  Companj'  iri  Oil  Canyon  about  33 
miles  northeast  of  Summerland.  The  rocks  here  exposed  are  the  overturned  upper 
Topatopa  shale,  which  dips  steeply  at  angles  ranging  from  60°  N.  to  vertical ;  oil  springs 
occur  in  them  in  the  immediate  neighborhood  of  the  wells.     The  wells  start  down  in 


>Bull.  California  State  Mining  Bureau.     No.  19,  1900,  p.  104. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  Ill 

the  shale,  but  may  penetrate  to  the  stratigraphically  higher,  but  actually  lower  upper 
sandstone  bolt.  The  wells  are  between  ;"iOO  and  600  feet  deep,  and  yielded  small  quan- 
tities of  oil  and  much  gas. 

"Seven  wells  and  one  tunnel  havo  been  sunk  by  the  Occidental  Mining  and  Petroleum 
Company  in  Toro  Canyon,  about  SJ  miles  nortlieast  of  Sumnierland  and  three-fourths 
of  a  mile  west  of  those  of  the  Santa  Barliara  Oil  Company  just  described.  The  for- 
mation at  the  Occidental  wells  is  tlie  same  as  tliat  in  Oil  Cannon,  and  tbc  wells  doubtless 
derive  their  oil  from  the  same  zone.  The  wells  range  in  depth  from  200  to  1100  feet. 
Four  of  tliem  were  classed  as  productive  and  tlirec  dry.  altliougli  tlie  latter  contained 
traces  of  oil.  No.  1  is  said  to  have  produced  a  total  of  .")000  barrels  and  No.  5  was 
rated  as  a  five-barrel  well  ;  thf  average  for  tlie  productive  wells  was  about  two  to  three 
barrels  a  dav  each.  In  August.  1895.  only  one  well  was  pumping,  and  the  oil  from  this 
was  largelv' mixed  with  water.  The  oil  is  black  and  of  17°  Baume  gravitv  when  it 
first  comes"  from  th-3  wells,  but  on  standing  for  a  little  while  drops  to  14°.  The  tunnel 
is  'i^^  feet  long  and  inns  in  a  N.  1*1°  K.  direction  into  tlie  mountains.  It  penetrates 
sandstone  composed  of  quartz,  feldspar  and  green  and  reddish  minerals,  interbedded 
witli  the  grcenisli  slialc.  It  yielded  little  oil  Init  much  water,  and  tlie  latter  is  now 
being  used  in  Summerland.     An  analysis  of  tliis  water  is  given  on  page  24. 

"The  well  of  the  Santa  Monica  Oil  Company  is  located  two  miles  nortli  of  Tarpinteria, 
near  the  mouth  of  Santa  ^lonica  Canyon.  It  starts  down  in  the  lowest  Sespe  sand- 
stone, which  here  dips  60°  S.,  10°  W..  and  penetrates  the  alternating  .sandstone  and 
shale  of  the  uppermost  Topatopa.  A  yield  of  fight  barrels  a  day  of  IS"  amber-colored 
oil  accompanied  bv  strong  gas  pressure  was  encountered  at  400  feet.  At  TOO  feet  a 
strong  flow  of  sulphur  water  'drowned  out'  the  oil  and  the  well  is  nosv  abandoned. 

"Tlie  I'inal  Oil  Company  is  nutting  down  a  well  at  the  mouth  of  Arroyo  Parida 
Canyon,  about  3.^  miles  east  of  Summerland.  It  penetrates  the  lowest  Sespe  sand- 
stone and  the  uppermost  Tojiatopa  alternating  sandstone  and  shales,  which  here  dip 
60°  S.  It  is  thought  that  the  well  will  reach  the  oil  in  sands  under  a  certain  shell  at 
a  depth  of  something  more  than  1000  feet. 

"General  Conclusion. 

"The  conditions  of  structure  do  not  appear  to  favor  the  probability  of  striking 
remunerative  deposits  of  oil  by  deep  drilling.  It  is  true  that  oil  would  probalily  be 
encountered  in  wells  2000  or  more  feet  in  depth  put  down  almost  anywhere  over  the 
territory  underlain  by  the  Monterey  shale,  but  the  steep  dips  and  close  texture  of  the 
shale  apparently  preclude  the  accumulation  of  such  great  deposits  of  oil  as  are  found 
in  fields  where  the  roi-ks  are  less  steeply  inclined  and  more  porous. 

"Region   Near  Carpinteria. 

"The  last  paragraph  is  as  applicable  to  the  region  about  Carpinteria  and  to  the 
east  as  far  as  the  contorted  condition  of  the  shale  extends  as  it  is  to  that  territory 
about  Summeiland  which  is  underlain  by  the  Monterey.  More  or  less  oil  is  inclosed 
in  the  shale  and  in  local  interbedded  sandstones,  but  it  does  not  appear  likely  that 
heavy  producers  will  ever  be  encountered  in  a  region  of  such  distortion  and  fracturing 
as  is  prevalent  in  tlie  Monterey  shale  all  along  this  part  of  the  coast,  although  in  certain 
facies  of  the  shale  fracturing  .seems  to  be  essential  to  the  migration  of  the  oil  within  or 
through  it. 

"Region    West    of    Monteclto. 

"It  is  thought  that  wells  sunk  deep  enough  to  penetrate  the  basal  beds  of  the  Fer- 
nando formation  in  the  region  of  the  Montecito  anticline,  which  extends  indefinitely 
west-northward  from  the  coast  one  mile  west  of  Montecito  Landing,  will  strike  deposits 
of  oil  of  about  the  same  quality  as  the  best  of  that  encountered  at   Simimerland. 

"Region  of  the  Topatopa   Formation    (Eocene)    Northeast  of  Summerland. 

"In  the  light  of  the  development  which  has  already  taken  place  in  Toro,  Oil,  Santa 
Monica  and  Arroyo  Parida  canyons,  it  seems  almost  certain  that  light  producers 
(averaging  from  two  to  six  or  eight  barrels  a  day  of  14°  to  18°  oil),  lOOO  feet  or  less 
in  depth,  could  be  put  down  at  many  place.s  along  the  contact  between  the  upper  Topa- 
topa shale  and  sandstone  zones  or  the  contact  between  the  Topatopa  and  Sespe  forma- 
tions in  the  region  northeast  of  Summerland.  The  oil-bearing  strata  in  both  of 
these  belts  are  apparently  confined  to  the  upper  part  of  the  Topatopa,  and  to  obtain 
productive  wells  is  simply  a  question  of  locating  places  whore  the  structure  appears 
most  advantageous  for  the  accumulation  of  the  petroleum.  The  region  near  the 
Arroyo  Parida  fault,  toward  the  east  end  of  the  area  covered  bv  the  map,  appears 
promising,  although  the  wells  here,  especially  on  the  north  side  of  the  fault,  would 
have  to  go  much  deeper  to  strike  the  oil  zone  than  they  do  at  the  tested  localities." 

In  Bulletin  63,  .California  State  ^Mininer  Bureau,  "Petroleum  in 
Southern  ("alifornia."  l)y  Paul  AV.  Prutznum,  liJl:},  pages  ;«9-415,  a 
complete  list  of  all  wildeat  wells  in  the  county  and  their  results  up  to 
1913  is  given.  McLaughlin  and  AVaring^,  in  their  bulletin,  give  a 
somewhat  briefer  account  of  Santa  Barbara  County. 

'California  State  Mining  lUiroau.  Bull  69.  Petroleum  Industry  of  California,  1914. 
By  R.  P.  Mcl.^ughlin  and  C.  A.  Waring. 


112  •    CALIFORNIA   STATE   MINING  BUREAU. 

Ventura  County. 

The  topographic  features  of  Ventura  County  consist  of  a  high,  rugged 
mountainous  area  in  the  northern  half  of  the  county,  a  series  of  river 
valleys  draining  the  south  central  portion,  and  finally  another  moun- 
tainous area,  along  the  coast  in  the  southeast  quarter. 

The  mountain  area  of  the  northern  half  of  the  county  may  be  consid- 
ered as  the  meeting  place  of  the  Santa  Ynez  and  San  Rafael  ranges  with 
the  Tehachapi  IMountains.  The  elevations  of  the  different  peaks  vary 
from  3000  to  8800  feet.  The  Cu3'ama  River  drains  the  northwestern 
part,  and  Sespe  and  Piru  creeks  drain  the  southern  portion.  Pine 
Mountain  is  the  name  given  to  the  ranges  just  south  of  the  Cuyama 
River  and  the  ranges  just  south  of  Sespe  and  Piru  creeks  are  known  as 
the  Topatopa  Mountains. 

The  river  valleys  of  the  south  central  portion  are  three  in  number 
and  contain  the  proven  oil  fields  of  the  county.  The  most  northerly 
is  known  as  Ojai  Valley,  which  has  an  east  and  west  trend,  but  drains 
into  the  Pacific  through  the  north  and  south  trending  Ventura  River, 
Sulphur  Mountain,  a  25p0-foot  range,  separates  the  Ojai  from  the 
valley  of  the  Santa  Clara  River,  the  second  and  largest  of  the  group. 
South  Mountain  and  Oak  Ridge,  with  elevations  as  high  as  3000  feet, 
form  the  southern  boundary  of  the  Santa  Clara  and  separate  it  from 
the  Simi  Valley,  the  third  and  most  southerly  of  the  group. 

The  Santa  Monica  IMountains,  reaching  elevations  of  3000  feet,  lie  to 
the  south  of  the  Simi  Valley  and  foi  m  a  mountainous  area  along  the 
coast  in  the  southeast  quarter  of  the  county.  The  Santa  Clara  and  the 
Simi  join  west  of  South  Mountain,  forming  a  large  fertile  plain,  which 
continues  as  far  northwest  as  the  Ventura  River. 

GEOLOGY  AND  OIL  POSSIBILITIES  OF  THE  COUNTY. 
Northern  Half  of  the  County. 

The  mountain  area  of  the  northern  half  of  the  county  offers  little  or 
no  inducement  for  drilling.  The  northeastern  corner  in  the  vicinity  of 
Mount  Pinos,  Frazer  INIountain,  San  Rafael  Point  and  IMcDonald  Point 
is  occupied  by  a  mass  of  granitic  rock,  with  occasional  patches  of  lime- 
stone. Between  INIount  Pinos  and  Frazer  jMountain.  in  the  vicinity  of 
the  Lockwood  Valley_,  there  is  a  small  area  of  Tertiary,  and  seepages 
have  been  reported  from  this  area.  In  the  region  north  of  the  Cuyama 
Valley  and  south  of  the  Kern  County  line  and  east  of  the  Santa  Barbara 
County  line,  the  rocks  exposed  are  sediments  of  iMiocene  age.  A 
portion  of  this  area  has  been  mapped  by  the  United  States  Geological 
Survey^  and  no  evidence  of  oil  was  found. 

In  the  region  south  of  the  Cuyama  River,  west  of  Ozena  and  north 
of  the  headwaters  of  the  Sespe  Creek,  Fairbanks-  has  reported  that  the 
rocks  exposed  are  of  Chico  age. 

The  southern  portions  of  the  mountain  areas  are  composed  of  Avhat 
Eldridge  and  ArnokP  called  the  Topatopa  formation    (Eocene)    and 


'U.  S.  Geological  Survey.     Bull.  621-M.     Geology  and  Oil  Resources  of  the  Cuyama 
Valley.     By  W.  A.  Englisli,   1916. 

^Twelfth  Annual   Report  of  the  State  Mineralogist.     Geology  of  Northern  Ventura 
County.      By  H.  W.  Fairbanlis.      Pp.  493-526,  1894. 

nr.  S.  Geological  Survey.     Bull.  309.     The  Santa  Clara  Valley,  Puente  Hills  and  Los 
Angeles  Oil  Districts.     By  G.   H.  Eldridge  and  Ralph  Arnold. 


PETROLEUM    RESOURCES   OF    CALIFORNIA. 


113 


8—13322 


OAK  KIDGE  ANTICLINE,  VENTURA  C'UUNTY    (LOOKING   WEST  Fli  I IM  THE  SANTA  I'AIU.A  OIL  (.'O.'S  ritOI'EUTY  ;  STItATA  EXl'OSKH  AltE  THE  RED  AND  WHITE  SANDSTONE  BEDS  OF  TUB  SESPE  FORMATION;  AXIS  OF  THE 

FOLD  IS  AT  THE  LEFT  OF  THE  riCTUREl. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  113 

wliich  may  in'opcily  bo  divided  into  .Martinez,  Megano.s  and  Tejon.  In 
the  extreme  southern  portions  of  this  area  the  Topatopa  and  the  over- 
lying Sespe  (Oligoeene)  are  oil  bearing,  and  tliis  region  will  be  discussed 
ill  conneetion  with  the  pi'oven  fields  of  the  Ojai  and  lower  Sespe 
xaUeys.  The  statement  made  at  the  beginning  of  this  article,  that  the 
mountainous  area  of  the  northern  half  of  the  county  offers  little  induce- 
ment for  drilling,  is  based  on  the  highly-tilted  and  crushed  condition  of 
tlie  formations  and  the  total  lack  of  any  authentic  indications  of  petro- 
leum. I'lider  the  most  favoral)U'  conditions  the  most  that  could  be 
expected  from  a  mountainous  region  like  this  would  be  extremely  small 
wells. 

Central  Portions  of  the  County — Area  of  the  Proven  Fields. 

This  region  has  been  mapped  ])oth  by  the  United  States  Geological 
Survey^  and  the  State  Alining  Bureau,-  and  the  reader  is  referred  to 
these  reports  for  detailed  descriptions  of  these  areas,  as  only  a  general 
description  of  the  fields  with  possibilities  of  extension  will  be  given  here. 

OJAI  VALLEY  FIELDS. 

The  formations  consist  of  a  broad  mass  of  Monterey  shale  exposed 
along  Sulphur  Mountain  and  in  the  hills  north  of  the  upper  Ojai  Valley. 
Between  these  two  areas  of  Monterey  there  is  a  narrow  strip  of  Sespe 
red  beds  (Oligoeene).  The  contact  of  these  beds  with  the  Monterey  on 
either  side  is  that  of  an  overthrust  fault  (see  Fig.  7,  Sec.  AB).  The  oil 
which  has  been  formed  in  the  diatomaceous  shales  of  the  Monterey  has 
migrated  and  collected  in  the  overlying  sandstone  beds  of  the  Sespe  in 
the  vicinity  of  the  fault  zones.  The  principal  area  of  development  is 
on  the  property  of  the  Pan-American  Petroleum  Company  in  the  upper 
Ojai  Valley.  The  wells  are  located  in  an  area  between  the  two  faults 
and  penetrate  probal)ly  to  the  Sespe  beds  that  are  in  contact  with  the 
Monterey.  The  wells  are  small  and  the  oil  is  of  heavy  gravity.  The 
outlook  for  any  further  increase  in  production  is  doubtful.  The  most 
favorable  region  for  extending  the  limits  of  the  field  is  eastward  towards 
Sisar  Canyon,  along  the  axis  of  the  faults. 

An  attempt  has  been  made  to  secure  production  on  the  axis  of  an 
anticline  in  the  Sespe  beds  about  one  to  one-half  miles  south  of  Nordhoff. 
The  wells  known  as  the  Pirie  w^ells  obtained  slight  showing  but  were 
commercial   failures. 

The  Sisar  Creek  field  lies  about  two  miles  east  of  the  upper  Ojai  field 
above  described,  and  is  considered  as  a  part  of  the  Ojai  Valley  fields. 
The  field  lies  about  one-eighth  of  a  mile  north  of  the  east-west  trending 
portion  of  Sisar  Creek  and  between  Santa  Paula  Canyon  and  the  north- 
south  trending  portion  of  Sisar  Creek.  The  structure  and  geology  are 
as  follows:  The  two  overthrust  faults  which  are  the  dominant  structures 

'I'.  .S.  Geological  Survey.  Bull.  309.  Santa  Clara  Valley-Puente  Hills  and  Los 
Angeles  Oil  Districts.      By  G.  H.  Kklridge  and  R.  Arnold,  1907. 

V.  S.  Geological  Survey.  Bull.  691-M.  Structure  and  Oil  Resources  of  the  Simi 
Valley.     By  W.  S.  W.  Kew,  1919. 

-California  State  Mining  Bureau.  Bull.  63.  Petroleum  in  Southern  California.  By 
P.  W.  Prutzman,  1913.      Pp.  21-155. 

California  State  Mining  Bureau.  Bull.  69.  Petroleum  Industry  of  California.  By 
R.  F.  McLaughlin  and  C.  A.  Waring,  1914.     Pp.  381-402,  PI.  Ill,  map  folio. 

8—13322 


112  ■    CALIFORNIA    STATE   MINING   BUREAU. 


—  •  — »"g»' j«"  loj. — j-mj».  uvv. —  J.11C  oiri-iiia  V  lara  vaiiev,  i'uente  Hills  and  IjOS 

Angeles  Oil  Districts.     By  G.  H.  Eldridge  and  Ralph  Arnold. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  113 

whii'li  may  properly  bo  divided  into  ^fartinez,  ]\Iegano.s  and  Tejon.  In 
1  he  extreme  soutliern  portions  of  this  area  the  Topatopa  and  the  over- 
lying Sespe  (Oligocene)  are  oil  Ijearing,  and  this  region  will  he  discnssed 
in  connection  with  the  proven  fields  of  the  O.jai  and  lower  Sespe 
valleys.  The  statement  made  at  the  beginning  of  tliis  article,  that  the 
mountainons  area  of  the  northern  half  of  the  county  offers  little  induce- 
ment for  drilling,  is  based  on  the  liighly-tilted  and  crushed  condition  of 
the  formations  and  the  total  lack  of  any  authentic  indications  of  petro- 
leum. Tnder  the  most  favorable  conditions  the  most  that  could  be 
expected  from  a  mountainous  region  like  this  would  be  extremely  small 
wells. 

Central  Portions  of  the  County — Area  of  the  Proven  Fields. 

This  region  has  been  nuipped  both  by  the  United  States  Geological 
Survey^  and  the  State  ]\lining  liureau.'  and  the  reader  is  referred  to 
these  reports  for  detailed  descriptions  of  these  areas,  as  only  a  general 
description  of  the  fields  with  possibilities  of  extension  will  be  given  here. 

OJAI  VALLEY  FIELDS. 

The  formations  consist  of  a  broad  mass  of  Monterey  shale  exposed 
along  Sulphur  JNIountain  and  in  the  hills  north  of  the  upper  Ojai  Valley. 
Between  these  two  areas  of  Monterey  there  is  a  narrow  strip  of  Sespe 
red  beds  (Oligocene).  The  contact  of  these  beds  with  the  Monterey  on 
either  side  is  that  of  an  overthrust  fault  (see  Fig.  7,  Sec.  AB).  The  oil 
which  has  been  formed  in  the  diatomaceous  shales  of  the  Monterey  has 
migrated  and  collected  in  the  overlying  sandstone  beds  of  the  Sespe  in 
the  vicinity  of  the  fault  zones.  The  principal  area  of  development  is 
on  the  property  of  the  Pan-American  Petroleum  Company  in  the  upper 
Ojai  Valley.  The  wells  are  located  in  an  area  between  the  two  faults 
and  penetrate  probably  to  the  Sespe  beds  that  are  in  contact  with  the 
IMonterey.  The  wells  are  small  and  the  oil  is  of  heav}'  gravity.  The 
outlook  for  any  further  increase  in  production  is  doubtful.  The  most 
favorable  region  for  extending  the  limits  of  the  field  is  eastward  towards 
Sisar  Canyon,  along  the  axis  of  the  faults. 

An  attempt  has  been  made  to  secure  production  on  the  axis  of  an 
anticline  in  the  Sespe  beds  about  one  to  one-half  miles  south  of  Nordhoff. 
The  wells  known  as  the  Pirie  wells  obtained  slight  showing  but  were 
commercial  failures. 

The  Sisar  Creek  field  lies  about  two  miles  east  of  the  upper  Ojai  field 
above  described,  and  is  considered  as  a  part  of  the  Ojai  Valley  fields. 
The  field  lies  about  one-eighth  of  a  mile  north  of  the  east-west  trending 
portion  of  Sisar  Creek  and  between  Santa  Paula  Canyon  and  the  north- 
south  trending  portion  of  Sisar  Creek.  The  structure  and  geology  are 
as  follows :  The  two  overthrust  faults  which  are  the  dominant  structures 


'I'.  S.  Geological  Survey.  Bull.  309.  Santa  Clara  Valley^uente  Hills  and  Los 
Angeles  Oil  Districts.      By  G.  H.   Eldridge  and  R.  Arnold,  1907. 

U.  S.  Geological  Survey.  Bull.  691-M.  Structure  and  Oil  Resources  of  the  Simi 
Valley.     By  W.  S.  W.  Kew,  1919. 

-California  State  Mining  Bureau.  Bull.  G.3.  Petroleum  in  Southern  California.  By 
P.  W.  Prutzman,  1913.      Pp.  21-155. 

California  State  Mining  Bureau.  Bull.  69.  Petroleum  Industry  of  California.  By 
R.  F.  McLaughlin  and  C.  A.  W^aring,  1914.      Pp.  381-402,  PI.  Ill,  map  folio. 

8—13322 


114 


CALIFORNIA    STATE    MINING   BUREAU. 


O^ 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  115 

of  the  upper  Ojai  X'alli'V  iiieryi'  al>(»ut  oiic-rourth  ol"  a  mill-  iioi'tli  aiul 
oast  of  tlie  point  wluTe  Sisar  Creek  turns  from  a  south  direetion  and 
flows  oast.  From  tliis  point  oast  the  stiuoture  consists  of  a  single  over- 
thrust  fault,  in  whicli  the  oldei-  Ses[)e  and  T(ipat()i)a  beds  on  thi'  noi'th 
side  of  the  fault  have  been  thrust  over  tlu'  .Monterey  beds  of  Sulphur 
^lountain  region.  The  oil  has  migrated  from  the  diatomaceoiis  shale 
of  the  ^lonterey  and  eolleeted  in  the  sandstone  beds  of  the  Sespe  along 
the  contact.  The  majority  of  wells  are  located  north  of  the  fault  line 
and  start  down  in  the  Sespe.  penetrating  the  oil  sands  along  the 
fault  contact.  The  wells  are  small  and  there  is  little  possibility  of  any 
considerable  increase  in  production.  However,  the  eastward  limits  of 
the  field  towards  Santa  I'aula  Canyon  can  probably  bo  extended  with 
profit. 

In  .March.  1!)21.  the  total  proven  art'a  in  tlie  Ojai  Valley  field.s  was 
2J)7  acres.  In  December,  1!)20,  the  total  daily  production  was  192  barrels 
of  oil.  The  average  numl)or  of  wells  ]>i"oducing  at  this  time  was  42  and 
the  daily  average  proiluction  per  well  was  4.-1  barrels  of  oil  and  3.9 
barrels  of  water. 

SANTA  PAULA  FIELD. 

This  name  is  applied  to  a  number  of  isolated  areas  of  production 
lying  along  the  south  side  of  the  Sulphur  ^Mountain  and  Santa  Paula 
Ridge.  Those  areas  on  the  south  side  of  Sulphui-  ^Mountain  and  west 
of  Santa  Paula  are  found  at  the  heads  of  Aliso,  Wheeler  and  Adams 
canyons  and  those  on  the  south  side  of  Santa  Paula  Ridge  and  east  of 
Santa  Paula  are  foimd  at  the  head  of  Onlauf  and  Timber  canyons. 

Tlio  structure  that  luis  caused  the  accunuilation  of  the  oil  is  a  great 
overthrust  fault,  which  starts  at  the  extreme  western  end  of  Sidphur 
^Mountain  on  the  V^^ntura  River  and  runs  oast  along  the  south  flank  of  the 
mountain,  crossing  Santa  Paula  Canyon  about  one  mile  south  of  Sulphur 
.Mountain  Spi-ing  aiul  thence  continuing  to  the  ea.st  along  the  steep  south 
flank  of  Santa  Paula  Ridge  to  Timber  Canyon.  At  this  poinl  it  merges 
with  the  fault  from  the  Sisar  Canyon  field  and  the  two  continue  as  a 
single  fault,  running  northeast  around  the  l)as(^  of  ]Mount  San  Cayetano 
to  Sespe  Creek.  The  fault  zone  is  clearly  visible,  being  marked  by  a 
steep  escarpment,  along  Sulphur  ^Mountain  and  Santa  Paula  Ridge  and 
it  abruptly  terminates  the  headwaters  of  the  various  canyons  above 
mentioned. 

The  formation  lying  to  the  south  of  the  fault,  and  which  has  been 
overthrust  by  the  older  formations  to  the  north,  consists  of  Fernando 
sands,  clays  and  gravels.  The  formations  to  the  north  of  the  fault  consist 
of  the  broad  area  of  ^lonterey  slude,  occupyinu'  the  Sulphui-  ^Mountain 
region.  Owiiig  to  the  convergence  of  the  two  faults  at  Timber  Canyon, 
this  Monterey  area  gradually  thins  and  becomes  wedge  shaped  towards 
the  east  and  finally  disappears  entirely  at  Timber  Canyon.  From 
Timber  Canyon  east,  the  formation  luirth  of  the  fault  is  the  Topatopa 
sandstcme  and  shale.  The  magnitude  of  the  faulting  has  thrust  this 
formation  over  the  Fernando,  and  the  jMonterey  is  entirely  lacking  on 
the  surface  but  is  undoubtedlv  present  beneath  the  Fernando,  The 
south  end  of  Sec.  AB,  Fig.  7  shows  the  structure  on  the  south  side 
of  Sulphur  Mountain.     The  oil  has  formed  in  the  Monterey  and  has 


116  CALIFORNIA    STATE    MINING   BUREAU. 

collected  in  the  Fernando  sands  along  the  fault  contact.  The  oil  runs 
in  gravity  from  24*^  to  28°  Baume  in  the  Sulphur  area  and  averages 
about  32°  gravity  in  the  Timber  Canyon  area.  The  total  proven  area 
of  the  Santa  Paula  field  in  March,  1921,  was  approximately  170  acres. 
The  total  daily  average  production  in  December,  1920,  was  139  barrels 
of  oil.  The  average  number  of  welLs  producing  during  this  period  was 
65,  with  a  daily  average  production  per  well  of  2.2  barrels  of  oil  and  0.7 
of  water. 

The  wells  start  down  in  the  area  of  the  fault  zone  and  penetrate  to 
the  plane  of  contact,  the  average  de|)th  being  about  lOOU  feet.  The  width 
of  the  field  north  and  south  of  the  fault  is  limited  to  a  distance  of  about 
one-fourth  of  a  mile,  and  there  can  be  no  appreciable  extension  in  this 
direction.  In  an  east  and  west  direction,  along  the  axis  of  the  fault, 
tliere  is  much  room  for  development  and  there  is  apparently  no  reason 
why  there  should  not  be  a  continuous  line  of  small  wells  joining  up  the 
now  isolated  groups.  There  has  been  no  development  along  the  fault 
east  of  Timber  Canyon  and  this  area  affords  a  possibility  of  small  well 
development.  The  possibility  of  commercial  returns  depends  upon 
whether  the  overthrust  faulting  has  not  buried  the  oil  sands  at  too  great 
a  depth. 

VENTURA  FIELD. 

This  field  lies  along  the  Ventura  River  and  consists  of  two  proven 
areas.  The  most  southerly  area  is  about  two  and  one-half  miles  north- 
east of  the  town  of  Ventura  and  is  commonly  known  as  the  Ventura 
Avenue  field.  The  .structure  consists  of  a  simple  anticlinal  fold,  known 
as  the  Ventura  anticline,  trending  approximately  east-we.st,  and  crossing 
the  Ventura  River  at  right  angles.  This  fold  continues  westward  from 
the  river  for  a  distance  of  about  eight  miles,  finally  striking  out  to  sea 
about  one-fourth  of  a  mile  northwest  of  Sea  Cliff  Station.  Eastward  from 
the  river  it  extends  a  distance  of  about  six  miles,  chdng  out  on  Aliso  Creek. 
The  proven  area  consists  of  about  300  acres  on  the  axis  of  the  fold  at 
the  point  where  it  crosses  the  Ventura  River.  The  formations  exposed 
on  the  anticline  consist  of  Fernando  sands,  clays,  .shales  and  gravels. 
This  formation  acts  as  the  reservoir  for  the  oil,  which  wa.s  probably 
formed  in  the  underlying  IMonterey.  To  date,  two  oil  zones  have  been 
recognized — an  upper  or  light  oil  zone,  extending  from  1900  to  3000  feet 
and  yielding  oil  of  from  48°  to  56°  Baume  gravity ;  the  second,  or  heavy 
oil  zone,  is  found  below  3000  feet  and  yields  oil  of  from  30°  to  38°  Baume 
gravity.  The  light  oil  zone  at  one  time  gave  promise  of  being  capable 
of  producing  wells  as  high  as  150  barrels  per  day.  but  careless  drilling 
by  some  of  the  pioneer  companies  has  resulted  in  this  zone  being  flooded 
by  water,  so  that  the  present  production  is  extremely  small.  The  second 
zone  has  not  to  date  been  thoroughly  explored,  but  it  is  apparent  that  it 
is  capable  of  yielding  from  200-  to  300-barrel  wells  and  possibly  more 
in  deeper  sand  yet  to  be  encountered.  The  limits  of  the  field  have  not 
been  defined  and  it  is  probable  that  they  can  be  extended  for  some  dis- 
tance westward  from  the  Taylor  wells  of  the  Shell  Com]niny,  along  the 
axis  of  the  fold,  and  a  similar  extension  may  be  made  to  the  east  beyond 
the  Lloyd  wells  of  the  Associated  Oil  Company.     A  detailed  report  on 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  117 

the  iindergroiinil  condition  may  be  found  in  the  fifth  annual  report  of 
the  State  Oil  and  Gas  Supervisor.^ 

The  second  proven  area  on  the  Ventura  River  consists  of  a  small  sec- 
tion on  the  ea-st  side  in  the  vicinity  of  Fresno  Canyon  and  oast  of  La 
Crosse  Station,  covering  about  fifty  acres.  It  may  be  considered  as  a 
continuation  of  the  small  proven  areas  along  the  south  side  of  Sulphur 
^Mountain,  which  were  described  under  the  article  on  the  Santa  Paula 
field.  The  geolopy  and  method  of  accumulations  are  similar.  The 
yield  of  the  wells  is  small  and  the  commercial  value  of  the  district  is 
somewhat  doubtful.  There  is  no  doubt  but  what  the  area  could  be 
extended  eastward  along  the  fault  zone  as  far  as  the  producing  wells 
in  the  Aliso  Canyon,  a  distance  of  six  miles. 

Outside  of  the  two  areas  al)ove  mentioned,  there  is  apparently  no 
other  district  along  the  Ventura  River  that  offers  any  inducement  for 
drilling. 

In  the  district  lying  west  fnmi  tlie  Ventura  Kiver  to  the  Santa  Bar- 
bara County  line,  there  is  only  one  possible  area  of  development,  and 
that  has  been  described  under  the  article  on  the  Ventura  Avenue  field, 
namely  an  extension  of  this  field  along  the  axis  of  the  fold,  westward 
from  the  Taylor  wells  of  th-  Shell  Company.  It  is  most  probable,  how- 
ever, that  this  extension  can  not  be  carried  much  more  than  a  mile  west 
of  the  river.  The  extreme  westward  end  of  the  Venture  Avenue  anti- 
cline has  been  tested  in  two  wells  ])y  the  General  Petroleum  Corpora- 
tion and  f(.und  unproductive.  These  wells  were  known  as  the  Hobson 
wells.  Hol)son  No.  1  was  located  on  Padre  Juan  Canyon  and  Ilobson 
No.  2  on  ^ladranio  Canyon.  The  general  geology  of  the  remainder  of  the 
district  is  as  follows:  The  Fernando,  which  outcrops  along  the  axis 
of  the  Ventura  Avenue  anticline,  continues  northward  for  about  one 
and  one-half  miles  to  a  point  just  south  of  Red  ^lountain,  where  it  is 
abruptly  faulted  against  the  IMonterey.  This  Monterey  consists  of  a 
narrow  area  of  shale,  overlying  the  Sespe  beds  of  Red  ^Mountain.  It 
continues  westward,  coming  out  on  the  coast  between  Punta  Gorda  and 
Rincon  Point,  at  which  place  it  is  slightly  bituminized.  From  Red 
iNIountain  northward,  the  principal  formation  exposed  is  the  Sespe, 
consisting  mainly  of  red  and  white  sandstone  beds.  At  the  base  of  the 
Santa  Ynez  Range,  north  of  the  Santa  Ana  Valley,  it  rests  against  the 
Topatopa.  This  area  of  Sespe  contains  neither  favorable  structure  or 
any  indication  of  oil. 

District  Along  the  North  Flank  of  South  Mountain  and  Oak  Ridge. 

This  area  includes  two  proven  areas,  the  South  [Mountain  field  and 
the  Bardsdale-^lonteliello  district.  The  structure  may  be  considered. 
in  a  broad  sense,  as  that  of  a  great  anticlinal  fold  running  east  and  west 
along  the  north  flank  of  the  mountain,  from  Santa  Paula  to  Wiley  Can- 
yon. The  axis  of  the  fold,  however,  plunges  and  emerges  at  several 
different  points,  with  the  result  that  the  actual  structure  consists  of  a 
series  of  isolated  domes,  an  idealcondition  for  the  accumulation  of  oil. 
Beginning  at  the  west,  these  domes  are  four  in  number:  One  in  the 

'California  StatP  Mining.  Fifth  annual  report  of  the  State  Oil  and  Gas  Supervisor. 
Summary  of  Operation.s.  February,  1920.  Report  on  the  Ventura  Oil  Field.  By 
Lawrence  Vander  Leek, 


118  CALIFORNIA    STATE   MINING   BUREAU. 

vicinity  ol"  Moi'ji'an  and  AVillard  Canyon,  forming  tiio  South  ^luuntaiu 
field;  the  seeond  at  the  mouth  of  Grimes  Canyon,  forming  the  Bardsdale 
area ;  th(>  third  in  tlu^  vicinity  of  Guiberson  Canyon,  forming  the  ]\Ioute- 
bello  area;  and  finally,  the  fourth  in  the  vicinity  of  AVilcy  Canyon,  this 
last  area  being  unproven  to  date.  The  oldest  formation  in  the  district 
is  composed  of  medium  coarse  sandstone,  conglomerate  shales  and  clays 
of  vivid  red,  purple  and  white  coloi's.  These  beds  are  of  Sespe  age 
and  are  exposed  in  the  highest  points  of  the  several  domes.  From  an 
economic  standpoint  it  is  the  most  important  formation,  as  it  contains 
the  connnercial  oil  sand  of  the  district. 

Overlying  the  Sespe  red  beds  is  found  the  ^Monterey  series,  consisting 
of  Va<iueros  saiulstone  and  IMonterey  shale,  and  called  by  Eldridge  and 
Arnold  the  ^lodelo  formation.  This  formation  is  present  mainly  alojig 
the  high,  steep  ridge  that  marks  the  top  of  South  ilcuntain  and  Oak 
Ridge;  it  also  covers  the  axis  of  the  anticline  in  the  low  places  between 
the  several  domes.  The  ^Monterey  shale  is  bituminous,  and  burnt  shale 
areas  are  frequent,  especialh'  in  Grimes  Canyon.  These  areas,  however, 
have  no  connection  with  .the  proven  sands  of  the  district,  being  strati- 
graphically  several  thousand  feet  above  them,  and  any  oil  formed  by 
the  ^Monterey  would  collect  in  the  Fernando  sands  of  the  Las  Posas  area 
to  the  south.  Along  the  top  of  the  moun^^ain,  the  ^Monterey  is  overlaid 
by  the  Fernando,  which  dips  southward  to  the  Las  Posas  area  of  the 
Simi  Valley. 

The  oil  sands  of  the  proven  area  are  found  in  the  middle  and  lower 
Sespe  and  possibly  in  the  uppermost  Tejon.  The  exact  origin  of  the  oil 
is  not  entirely  clear,  but  it  is  generally  held  that  it  is  of  Eocene  origin, 
having  formed  in  the  carbonaceous  shales  of  tlie  underlying  Tejon  and 
^Meganos  formations.  The  extremely  light  gravity  of  the  oil  suggests 
an  Eocene  age. 

The  South  ^Mountain  field,  lying  just  south  of  the  town  of  Santa  Paula, 
is  at  ])resent  the  chief  productive  area  of  Ventura  County.  The  wells 
start  down  in  the  Sespe  and  shut  off  water  at  depths  from  400  to  800  feet. 
From  this  point  on,  oil  sands  are  encountered  to  depths  below  3000  feet. 
The  highest  point  of  the  donu^  is  in  the  vicinity  of  the  west  line  of  the 
Willard  lease.  From  this  point  the  axis  plunges  to  the  east  and  west. 
A  ph()tograi)h  of  this  area  is  shown  opposite  ])age  112.  The  dip  of 
the  north  flank  of  the  dome  is  rather  steep  and  the  outlook  for 
extending  the  field  to  the  north  is  doubtful.  The  south  flank,  how- 
ever, is  more  encouraging,  owing  to  the  gentler  dips,  and  it  is  probable 
that  the  field  can  be  extended  as  far  south  as  the  top  of  the  high  ridge. 
The  ])lunge  of  the  dome  has  limited  the  field  in  east  and  west  directions 
and  it  is  not  probable  that  commercial  wells  will  be  found  beyond  the 
w'est  line  of  Sec.  13,  or  beyond  the  east  line  of  See.  18.  The  field 
has  no  water  ti'ouble.  due  mainly  to  the  excellent  protective  work  of  the 
Oak  Ridge  and  Santa  Paula  Oil  Companies,  who  operate  the  major  por- 
tion of  the  area.  The  total  proven  area  in  IMarch,  1920,  was  330  acres, 
and  it  is  probable  that  future  drilling  will  cause  the  figure  to  be  doubled. 
The  total  daily  average  ]u-oduction  in  December,  1920,  was  3042  barrels 
of  oil.  The  average  number  of  wells  producing  was  23,  with  a  daily 
average  production  per  well  of  130  barrels  of  oil  and  no  water.  The 
gravity  of  the  oil  averages  about  30°  Baume. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  119 

The  intervening  area  between  the  South  ^Fountain  field  and  the  Bards- 
dale  area  is  about  four  miles.  This  district  otfers  no  inducement  for 
(Irilliiifi,  as  the  sharp  i)lunire  of  the  anticline  has  buried  the  Sespe  sands 
l)eyond  reach  of  the  drill  over  tiie  j^freater  portion  of  the  ai'ea.  The 
Schieferle  wells  of  the  Tnited  Oil  Company,  on  Sec.  17,  T.  3  N.,  R.  20  \V., 
have  demonstrated  that  even  when  they  are  accessible  to  the  drill  west 
of  Sec.  18,  their  oil  content  is  small. 

The  Bardsdale  area  consists  of  a  dome  in  the  Sespe  at  the  mouth  of 
Grimes  Canyon.  This  fii^ld  is  the  least  productive  of  the  South  ^lountain 
group.  Its  limits  are  practically  set  and  no  increase  in  the  production 
is  likely.  The  total  proven  area  in  ]\Iarch,  11)21,  wa.s  130  acres.  Two 
miles  east  of  the  Bardsdale  area  is  the  Montebello  area  (this  should  not 
be  confused  with  the  .Montcbdlo  field  of  Los  Angeles  County),  which, 
previous  to  the  opening  up  of  the  South  ^lountain  field,  was  the  prin- 
cipal ])ro(]ucing  area  of  Ventui-a  County.  The  field  is  centered  about  a 
gently  diiiiung  dome  in  the  Sespe.  The  proven  area  lies  in  the  middle; 
of  Sees.  3  and  4,  T.  3  X.,  R.  19  AV.  Three  well-defined  oil  zones  and 
two  intervening  salt-water  zones  are  recognized.  The  first  oil  zone  is 
shallow  and  the  yield  is  small.  The  second  oil  zone,  encountered  fi'om 
appro.xiniately  KiOO  to  2500  feet,  is  the  chief  source  of  production  and 
is  located  near  the  base  of  the  Sespe. 

The  third  zone,  of  which  little  is  known  to  date,  yields  light  oil  and 
may  be  in  the  Te.ion.  AYhile  the  limits  of  the  field  have  been  fairly  well 
defined,  there  is  still  I'oom  for  considerable  development  work  around 
the  edges.     The  total  i)roven  area  in  ^larch,  1!)21,  was  310  acres. 

Between  the  Bardsdale  and  the  Montebello  area  there  is  at  least  one 
fair  chance  for  development.  This  consists  of  a  plunging  anticline 
running  across  the  northeast  corner  of  Sec.  6  and  the  NW.  -|  of  Sec.  5, 
T.  3  N..  R.  li)  \V.  The  general  trend  of  the  anticline  is  to  the  southeast, 
with  a  sharp  jdunge  in  that  direction.  The  highest  |)art  of  the  struc- 
ture is  api)ai"cntly  along  the  north  line  of  Sec.  <>.  The  Petroleum 
]\lidway,  in  the  northwest  corner  of  Sec.  5,  drilled  a  well  and  encoun- 
tered a  fair  showing  of  oil  between  2500  aiul  ;3000  feet.  The  well,  how- 
ever, was  abandoned  on  account  of  mechanical  difficulties.  The  Oak 
Ridge  Oil  Company  has  a  well  about  one-fourth  of  a  mile  south  of  the 
Petroleum  Midway  location,  and  has  to  date  only  encountered  gas.  The 
Amalgamated  Oil  Company  is  also  testing  the  area  out  with  a  well  in 
the  northeast  corner  of  Sec.  6.  The  Bardsdale  and  IVIontebello  areas 
are  regarded  as  one  field  and  the  district  is  commonly  known  as  the 
Bardsdale  field.  The  total  daily  average  production  in  December,  1020, 
was  1340  barrels  of  oil.  The  avei'age  number  of  wells  producing  was 
134.  with  a  daily  average  production  per  well  of  10  barrels  of  oil  and 
1.1  of  water.  The  gravity  of  the  oil  averages  about  25°  Baume.  About 
two  miles  east  of  the  Montebello  area  occurs  the  last  and  most  easterly 
dome  in  the  Sespe.  along  the  north  flank  of  Oak  Ridge.  This  dome  is 
located  on  Sec.  1,  T.  3  N.,  R.  19  W.,  and  may  be  called  the  Wiley  Canyon 
dome.  This  area  remains  unproven  today.  Two  wells  have  been  drilled 
here  and  abandoned,  but  the  records  and  results  are  lacking.  The  sur- 
face evidence  indicates  conditions  similai-  to  the  Monteliello  area,  and 
it  may  be  considered  worthy  of  testing. 


120  CALIFORNIA    STATE   MINING   BUREAU. 


SESPE  CANYON  AREA. 


This  district  includes  the  territory  drained  by  the  Big  and  Little 
Sespe  and  their  branches.  Some  of  the  ilrst  development  work  in  Yen- 
tnra  County  took  place  in  this  area.  Of  late  years,  however,  on  account 
of  the  small  yield,  development  work  has  lagged.  At  the  present  time 
the  producing  areas  are  confined  to  the  E.  -J  of  Sec.  1,  T.  4  N.,  R.  20  W., 
at  the  junction  of  the  Big  and  Little  Sespe  Creeks;  and  to  an  area  on 
the  Little  Sespe  in  Sec.  6,  T.  4  N.,  R.  19  W.,  and  finally  on  the  head- 
waters of  Tar  Creek,  in  Sec.  33,  T.  5  N.,  R.  19  W. 

The  geology  and  structure  are  more  or  less  complicated.  The  forma- 
tions exposed  consist  mainly  of  the  Vaqueros,  the  Sespe  and  the  Topa- 
topa  beds. 

The  structure  consists  of  a  number  of  sharply-folded,  plunging  anti- 
clines and  s>nclines,  in  some  cases  overturned.  The  oil  apparently  has 
been  formed  in  the  shales  of  the  Topatopa  formation  and  has  migrated 
and  collected  in  the  sandstones  at  the  base  of  the  overlying  Sespe.  The 
gravity  of  the  oil  varies  considerably.  AVells  on  the  Big  Sespe  showed 
heavy  black  oil  of  about  13°  Baume.  The  Tar  Creek  wells  i)roduce 
medium  gravity  oil  of  about  26'  Baume.  The  Kentuck  wells  also 
average  about  26°  Baume.  The  wells  on  the  Little  Sespe  run  about 
20°  Baume.  The  average  depth  of  the  wells  is  about  900  feet.  There 
is  no  water  trouble.  The  total  proven  area  in  ^Nlarch,  1921,  was  440 
acres,  this  figure  being  based  on  the  actual  present  production.  It  is 
probable,  however,  that  if  the  old  abandoned  properties  which  could 
easily  be  made  productive  were  considered,  the  proven  area  would  be 
doubled.  The  total  daily  production  from  the  field  in  December.  1920, 
averaged  about  100  barrels  of  oil.  The  total  number  of  wells  producing 
was  21,  with  an  average  daily  production  per  well  of  4.5  barrels  of  oil 
and  0.8  of  water.  There  is  still  considerable  room  in  the  field  for  small 
well-development.  The  most  favorable  locations  are  along  the  axis  of 
the  anticline  in  the  vicinitv  of  the  Los  Angeles  Oil  Company  wells,  on 
Little  Sespe  Creek ;  on  Sees.  21,  28,  32  and  33,  T.  5  N.,  R.  'l9  W.,  all 
located  about  the  headwaters  of  Tar  Creek ;  on  See.  1,  T.  4  N.,  R.  20  W., 
in  the  vicinity  of  the  plunging  overturned  syncline  from  which  the 
Kentuck  wells  are  producing,  and  in  the  northern  portion  of  the  same 
sections  along  the  axis  of  an  anticline  running  through  the  Big  Sespe 
Oil  Company's  wells.  The  area  along  Big  Sespe  Creek  is  not  so  encour- 
aging, on  account  of  the  heavy  oil  ]U'oduced.  On  Coldwater  Creek,  just 
above  Devil's  Gate,  there  is  a  well-defined  anticline  which  is  probably 
capable  of  yielding  heavy  oil.  Many  of  the  old  abandoned  properties 
are  also  capable  of  being  repaired  and  put  on  a  producing  basis. 

PIRU  FIELD.. 

This  name  is  given  to  a  group  of  proven  areas  lying  north  and  soutli 
of  the  Santa  Clara  River  in  the  vicinity  of  the  towns  of  Piru  and 
Camulos.  The  proven  areas  north  of  the  Santa  Clara  are  located  between 
Hopper  Canyon  and  Piru  Creek.  South  of  the  Santa  Clara  they  are 
located  along  Torrey,  Eureka  and  Topo  canyons.  The  unproven  area 
between  Hopper  Canyon  and  Sespe  Creek  and  between  Piru  Creek  and 
the  Los  Angeles  County  line  will  also  be  considered  here. 


PETROT-EUM    RESOURCES   OF    CALIFORNIA.  121 

The  general  structure  of  these  areas  consists  of  sharply-folded  anti- 
clines and  synclines.  The  oil-bearing  formation  is  the  ]\Ionterey 
(Modelo),  the  production  coming  from  sandstone  beds  (probably 
Vaqueros)  interbedded  in  the  organic  shale.  From  Piru  Creek  east 
to  the  Los  Angeles  County  line,  the  principal  formation  exposed  is  the 
Fernando,  which,  however,  appears  to  be  barren  of  any  appreciable 
amount  of  oil. 

Following  is  a  portion  of  ^McLaughlin  and  Waring 's  report  on  this 
region : 

"East  of  the  Sespe  and  Fourfork  creeks  the  geologic  formations  are  folded  along 
nortliwest-southoast  axes  which,  witli  a  few  exceptions,  turn  to  an  east-west  direction 
east  of  Hopper  Canvon.  The  Vaqueros  and  Monterey  are  the  important  oil  formations 
In  this  region.  Most  of  the  drilling  has  been  done  in  the  canyons  where  they  cut 
across  likciv  anticlines. 

"Probably  the  most  favorable  drilling  territory  in  this  vicinity  is  along  the  north 
flank  of  the  Nigger  Canyon  anticline  and  along  the  Hopper  Canyon  anticline.  There 
are  exposures  of  oil  sand  in  the  Vaqueros  formation  on  the  west  face  of  Oat  Mountain, 
and  also  in  the  Monterey  formation  from  tlie  mouth  of  Pole  Canyon  to  Fairview  Canyon. 

"The  principal  oil  zones  are  tliose  of  the  Monterey  (lower  Modelo)  formation,  con- 
sisting of  shallow  sand  interbedded  in  the  Monterey  shale,  and  those  of  the 
Vaqueros  sandstone  Interbedded  in  the  Vaqueros  shale.  The  oil  zones  of  the  Monterey 
range  to  1000  feet  below  the  surface,  while  those  of  the  Vaqueros  range  usually  from 
1500  to  2000  feet. 

"The  maximum  initial  production  per  day  for  some  of  the  older  wells  of  the  Sunset, 
Modelo  and  Harris  Oil  Companv  was  7.5  barrels.  Wells  as  a  rule  drop  off  rapidly  for 
the  first  few  months  and  then  maintain  a  more  steady  production  for  many  years  at 
rates  of  from  n  to  25  barrels.  The  oil  varies  from  14°  Baume  in  the  shallower  Sunset 
and  Harris  wells  to  over  30°  Baume  in  some  of  the  Modelo  wells.  The  deepest  Harris 
well  obtained  the  lightest  oil  and  the  largest  production  of  the  group.  In  the  long  run 
wells  over  2500  feet  deep  are  said  to  be  no  more  profitable  than  shallower  ones. 

"A  few  wells  have  been  drilled  as  far  east  as  San  Martinez  Chiquito  Canyon  and 
Castaic  Valley.  These  wells  started  in  the  Fernando  formation  and  drilled  to  depths 
ranging  from  500  to  2500  feet.  Traces  of  oil  and  asphalt  are  reported  from  some  of 
these  wells.  Probably  if  oil  in  paying  quantities  is  struck  in  this  region  it  will  be 
deep  because  of  the  eastward  plunging  of  the  geologic  structural  axes." 

Following  is  a  portion  of  Eldridge  and  Arnold's  report  on  the  Torrey, 
Eureka  and  Tapo  canyons  group  of  wells : 

"The  productive  territory  of  the  Torrey  anticline,  forming  what  is  known  as  the 
Torrey  field,  embraces  an  area  of  about  one  square  mile,  the  length  being  twice  tlie 
breadth  and  lying  with  the  strike  of  the  rocks,  which  gradually  bend  from  N.  65°  W., 
the  direction  prevailing  on  tlie  side  of  the  flexure,  to  northwest,  north-northwest,  and 
north  as  the  strata  round  its  end.  The  axis  of  the  anticline  passes  close  to  the  northern 
edge  of  the  field,  the  wells,  with  a  few  exceptions,  having  been  drilled  in  the  strata  of 
gentler  dip,  30°  to  40°.  south  of  the  axis.  In  all  there  are  between  50  and  60  wells, 
aligned  in  seven  or  eight  concentric  arcs,  in  accordance  with  tlie  curves  assumed  by 
the  outcropping  strata.  Tlie  wells  nearer  the  axis  penetrate  the  red  and  gray  banded 
argillaceous  sandstone  that  has  been  correlated  with  a  portion  of  the  Sespe  formation, 
while  those  more  distant  are  perhaps  entirely  confined  to  the  sandstone  and  shale  of 
the  Vaqueros. 

"It  is  said  to  be  usually  impossible  in  this  field  to  identify  horizons  in  one  well  with 
those  in  another,  even  though  the  two  locations  are  adj.acent.  Tlie  oil  sands  also  vary 
in  thickness  from  a  few  feet  to  150,  and  even  the  thicker  beds,  it  is  reported,  cannot 
be  identified  from  well  to  well.  It  is,  however,  the  opinion  of  the  writer  that  consider- 
able order  might  be  worked  out  with  the  aid  of  carefully  prepared  cross  sections. 

"Tlie  oil  has  a  gravity  of  30°  to  35°  Baume  and  resembles  that. derived  from  the 
same  formation  north  of  the  Santa  Clara,  especially  that  from  the  region  of  Fourfork 
and  Tar  creeks.  The  depth  of  the  wells  varies  from  GOO  to  2000  feet,  the  deeper  wells 
being  those  farther  away  from  the  axis  of  the  fold.  North  of  the  Torrey  anticline  the 
productive  territory  is  apparently  confined  to  the  east  end  of  the  field  where  the  distance 
from  the  syncline  immediately  north  and  from  the  fracture  possibly  accompanying  it 
is  greatest. 

"Concerning  the  extent  of  the  Torrey  field  beyond  the  present  developed  area,  it  may 
be  said  with  some  degree  of  assurance  that  to  the  west  and  north  it  is  likely  to  be 
limited  by  structural  conditions'  to  nearly  the  existing  lines.  In  the  other  directions 
no  prediction  can  be  made. 

"Eureka    Wells. 

"The  wells  of  Eureka  Canyon  are  located  in  its  lower  reaches,  most  of  them  being 
grouped  at  the  sharp  turn  half  a  mile  above  its  mouth.  The  geology  of  tlie  immediate 
region  is  somewhat  doubtful,  but  if  the  structure  is  that  of  a  highly  compressed  com- 
pound fold,  as  suggested  on  page  S2.  the  locus  of  the  wells  is  not  far  from  its  anticlinal 
axis  ;  moreover,  the  developed  territory  is  in  the  vicinity  of  a  prominent  ?urve  in  the 
stratification  planes,  the  axis  having  been  pushed  somewhat  northward  between  Eureka 


122  CALIFORNIA    STATE    MINING   BUREAU. 

and  Torrey  canyons.  The  wells  penetrate  the  Vaqueros  sandstone,  conglomerate  and 
shale,  but  whether  any  of  the  beds  are  duplicated  it  is  impossible  to  determine.  Suoh 
duplication  may  have  taken  place,  but  it  has  had  practically  no  effect  on  the  productive- 
ness of  the  territory.  The  wells  are  located  a  little  over  a  mile  north-northeast  of  the 
Torrey  group,  the  geology  of  the  two  fields  being  Quite  distinct. 

"Twenty-one  wells  were  in  operation  or  drilling  at  tlie  time  of  the  writer's  visit. 
They  vary  in  deptli  from  600  to  1200  f(>et.  and  the  strata  passed  through  according  to 
the  logs,  "embrace  sand,  arenaceous  shale,  dark,  adobe-like  clay,  and  the  usual  'hard 
shells'  of  the  drillers.  The  cliaracter  of  the  beds  varies  every  50  to  125  feet  in  depth, 
but  sandstone  predominates.  Oil  .sand,  so-called,  appears  to  be  encountered  at  depths 
of  540  to  620  feet.  Water  is  found  botli  in  the  upper  parts  of  the  wells  and  beneath 
the  lowermost  oil  sand  recorded.  Well  No.  20,  of  the  group  at  the  turn  of  the  canyon, 
is  the  only  one  in  which  pebbles  are  reported.  Thesie  are,  perhaps,  a  local  development 
of  one  of  the  more  prominent  sandstones  that  lie  near  either  the  summit  or  the  base 
of  the  Vaqueros  beds.  Usually  but  a  single  oil  sand  shows  in  a  well,  and  tt  is  the 
opinion  of  the  superintendent  that  tlie  producing  horizon  is  the  some  tliroughout  the 
field. 

"The  gravity  of  the  oil  averages,  it  is  said,  24°  Baum§,  but  in  some  instances  rises 
to  2  6°.  This  difference,  as  compared  witli  the  Torrey  oil,  is  inexplicable,  for  both  are 
believed  to  be  derived  from  the  same  formation.  Their  horizons,  however,  may  be 
different,  and  in  the  Eureka  field  the  sediments  appear  to  be  coarser,  while  the  strata 
are  far  more  fractured,  if  tlie  interpretation  of  the  geolog>-  here  given  is  correct.  The 
latter  feature  would  tend  to  permit  the  easier  escape  of  the  lighter  hydrocarbons,  leaving 
behind  the  heavier  oils,  which  now  constitute  the  product. 

"The  yield  has  been  from  1  to  4  0  barrels  per  day.  The  field  has.  however,  never 
been  one  of  large  production,  but  from  the  records  the  wells  appear  to  have  maintained 
their  suppl.v  witli  remarkable  uniformity. 

"No  evidence  of  the  red  and  gray  banded  series  of  probable  Eocene  age  has  been 
found  in  any  of  the  holes  in  this  field. 

"Wells  have  Vjeen  drilled  in* the  main  fork  of  Tapo  Canyon  and  also  in  each  branch 
of  a  westerlv  tributary.  Those  at  present  producing  lie  along  the  east  fork  of  this 
tributary.  They  are  four  in  number,  although  from  their  designation.  Nos.  12  to  15 
inclusive,  it  is  to  be  inferred  that  several  otliers  have  been  in  existence  in  earlier  days. 
Indeed,  one  or  two  of  these  old  wells  still  contain  a  slight  amount  of  oil.  The  producing 
wells  are  sunk  in  northward-dipping  sand.«tone  and  shale  a  mile  north  of  the  axis  of 
the  Tapo  anticline.  They  yield  at  present  from  5  to  4  0  barrels  of  oil  per  day.  The 
gravity  is  20°  to  24°  Baume,  the  20°  oil  being  produced  by  the  well  highest  up  in  the 
canyon  and  lowest  as  to  the  strata  penetrated.  These  wells  are  about  200  feet  apart 
and  range  in  depth  from  4  60  to  1200  feet.  The  oil  sand  is  encountered  at  235,  465.  940 
and  865  feet,  from  the  well  farthest  up  the  creek  to  that  lowest  down,  respectively. 
The  wells  lowest  on  the  dip  are  the  greatest  producers.  The  dip  of  the  measures  is 
from  50°  to  60°.  and  it  is  impossible  to  say  that  a  single  bed  produces  oil  for  the  entire 
field,  althougli  this  is  suggested  by  the  increasing  depths  of  the  wells  in  the  direction 
of  the  dip.  More  or  less  water  is  pumped  with  the  oil.  and  it  is  the  opinion  of  the 
superintendent  that  the  two  are  mined  and  come  from  the  same  bed.  The  amount  of 
water,  liowever.  is  sliglit.  the  proportion  being  given  as  1  of  water  to  40  of  oil.  Inas- 
much as  water-bearing  sands  overlie  the  oil  sands  it  may  be  tliat  a  leak  occurs  which 
would  account  for  its  presence  with  the  oil.  Water  was  also  found  beneath  the  oil 
sand  in  the  well  farthest  up  the  gulch  and  has  been  encountered  in  some  of  the  wells 
now   abandoned. 

"The  whole  of  the  lower  half  of  the  Vaqueros  strata  exposed  in  Tapo  Canyon  shows 
a  greater  or  less  impregnation  with  petroleum.  No  unusual  amount  appears  to  have 
been  assembled  in  proximity  to  the  axis  of  the  main  anticline,  and  it  may  be  tliat  the 
productive  territory  is  a  particularly  rich  portion  of  the  series  of  beds  which,  from 
some  cause  or  otlier,  has  held  its  oil  better  than  the  great  mass  of  the  beds  in  the  region. 
From  the  surface  no  reason  can  be  seen  for  the  enrichment  of  one  portion  of  the 
formation  over  another  portion,  and  except  for  strong  seepages  in  proximity  to  the 
wells  one  locality  might  as  readily  have  been  chosen  for  development  as  another. 

"The  logs  of  the  Tapo  wells  sliow  a  succession  of  blue  clay,  brown  shale,  gray  sand- 
stone, fine  to  coarse,  and  in  one  instance  a  trace  of  conglomerate.  The  thicknesses  of 
these  several  materials,  wliich  are  constantly  repeated,  vary  from  5  to  200  or  more 
feet,  the  average  being,  perhaps,  between  20  and  75  feet." 

In  ]\rareh.  1921,  the  total  proven  area  was  865  acres.  The  total  daily 
average  production  in  December,  1920,  was  336  barrels  of  oil.  The 
average  number  of  wells  producing  was  75.  with  a  daily  average  pro- 
duction per  well  of  -4.5  barrels  of  oil  and  5.2  of  water.  The  area  is  not 
encouraging  except  for  a  small  well-development. 

SIMI  VALLEY  FIELD. 

The  Siini  field  lies  along  the  north  side  of  the  Simi  Valley  between 
Santa  Susana  and  Simi. 

The  chief  area  of  production  is  around  the  month  of  Tapo  Canyon. 
From  there  on  west  to  Brea  Canvoii  there  are  a  few  scattering  wells. 


PETROLEl'M    RESOURCES   OF    CALIFORNIA.  123 

Tlic  iiiaiii  stnu-tiu-e  consists  of  the  Sinii  antielino.  This  fold  starts 
about  one-half  mile  east  of  the  mouth  of  Tapo  Canyon  and  runs  due 
west  to  a  point  just  west  of  the  canyon,  where  the  strike  of  the  axis 
ehangfes  to  a  soutlnvest  direction,  so  that  it  crosses  Hrea  Canyon  at  its 
mouth.  The  dips  on  the  tlanks  vary  from  15°  to  30°  and  there  is  a  plunfie 
to  the  axis  of  ai>proximately  3°  to  the  southwest.  East  of  Tapo 
Can>on  the  formation  exposed  on  the  axis  of  the  fold  is  of  Tejon  age. 
West  of  the  canyon  the  jdun^e  of  the  folds  has  caused  the  Sespe  to  overlie 
the  Tejon. 

TAPO  CANYON  WELLS. 

In  the  vicinity  of  the  Tapo  Canyon  wells  (principally  of  the  Pan- 
American  I'etroleum  Company)  the  oil  has  ajiparently  been  formed  in 
the  carbonaceous  shales  of  the  ^Meg-anos  (Koeenc)  and  has  eolleeted 
maiidy  in  the  overlyinji  sands  of  the  Tejon  and  to  a  lesser  extent  in  the 
Sesjjc  formation.  TIk^  oil  is  of  a  lisiht-ijreen  color  and  averages  in 
gravity  about  38^  Baunie;  some  wells,  however,  produce  as  high  as 
42°  gravity  oil.  Along  the  axis  of  tlie  fold  the  first  oil  is  encountered 
at  about  300  feet  and  productive  sands  are  logged  down  to  1600  feet; 
wells  down  the  dip  are,  of  course,  deeper.  The  sands  are  extremely 
lenticular  and  no  correlation  is  possible  from  well  to  well.  The  field 
is  api^irently  limited  in  a  north  and  south  direction  to  an  area  of 
3000  feet  about  the  axis  of  the  fold.  Along  the  axis,  in  a  westward 
direction,  there  is  every  indication  that  the  field  may  be  extended  for 
a  considerable  distance.  Eastward  from  Tapo  Canyon  to  the  head 
of  the  valley,  the  possibilities  may  be  summed  up  as  follows:  There  is 
a  chance  for  small-well  production  of  three  to  four  barrels  per  day 
in  the  areas  between  Tapo  Canyon  and  the  first  large  canyon  to  the 
east  (a  nnle  distant  from  the  proven  area).  The  structure  consists  of 
the  eastward  end  of  the  Simi  anticline,  and  in  Sees.  2!)  and  30,  T.  3  N., 
R.  17  W.,  some  oil  has  accumulated  along  a  fault  in  the  Tejon.  At 
the  licjid  of  the  vallex'.  in  the  low  hills  north  of  the  state  highway,  the 
structiii-e  consists  of  a  monocline  dipping  about  25°  to  the  west.  The 
formations  beginning  at  Ihe  bottom  consist  of  the  Chico,  IMartinez, 
]\[eganos  and  Tejon.  It  is  possil)le  that  wells  sunk  in  the  Tejon  might 
yield  3  to  4  barrels  per  day.  In  the  general  area  north  of  the  Tapo 
field,  including  the  southern  slope  of  Oak  Ridge  and  the  Santa  Susana 
^Mountains,  the  prospects  of  any  development  are  unfavorable. 

Area  in  the  Vicinity  of  Brea  Canyon. 

Westward  from  Tapo  Canyon  there  are  three  small  groups  of  wells. 
The  first  consists  of  the  Simi  wells  of  the  Pan-Anu'rican  Petroleum. 
These  are  located  near  the  west  cpiarter  corner  of  Sec.  34,  T.  3  N., 
R.  18  AV.,  and  consist  of  five  wells,  only  one  of  which  is  producing. 
The  wells  start  down  in  the  Sespe  about  three-quarters  of  a  mile  north 
of  the  axis  of  the  Simi  anticline  and  eiu'ouiiter  oil  sands  from  1600  to 
2100  feet.  The  oil  is  black  and  of  about  20°  Baume  in  gravity.  The 
yield  is  apparently  going  to  average  al)out  20  barrels  per  well.  The 
axis  of  the  fold  has  not  yet  been  tested  in  this  vicinity.  The  second 
and  third  groups  are  located  in  Brea  and  Los  Alamos  canyons,  and 
consist  of  the  Tninn  Oil  Company,  Cafiada  del  La  Brea  wells  and  the 


r 

124  CALIFORNIA    STATE    MINING   BUREAU. 

Pan-Amei-iean  Scarab  -wells.  The  Union  wells  are  in  Brea  Canyon, 
about  one  mile  north  of  the  axis  of  the  Siini  antieline,  and  the  Scarab 
wells  are  in  Los  Alamos  Canyon  abont  1|  miles  north  of  the  axis  of  the 
anticline.  Jnst  sonth  of  the  Union  wells  tliere  is  a  prominent  line  of 
oil  sands  and  seepages  which  may  be  followed  to  the  west  of  Brea 
Canyon  for  about  a  mile  and  a  half.  Both  groups  of  wells  are  appar- 
ently drawing  their  oil  from  these  outcrops,  the  dip  being  about  25°  to 
the  north.  The  beds  exposed  are  red,  purple  and  white  sands  and 
clays  of  the  Sespe  formation.  Tlie  oil  encountered  is  black  and  of 
about  18°  Baume  in  gravity,  the  yield,  per  well,  being  about  15  barrels 
per  day. 

At  the  mouth  of  Brea  Canyon,  a  mile  south  of  the  Union  wells,  are 
three  abandoned  dry  holes  all  located  approximately  on  the  axis  of 
the  Simi  anticline.  They  consist  of  the  Dabnc}-  &  Roberts  well,  in 
the  SEJ  of  See.  5.  T.  2  N.,  R.  18  W.,  which  was^  drilled  to  a  depth  of 
2680  feet :  the  ]\Iilev-Bulev  well  of  the  State  Consolidated  Oil  Company, 
in  the  SWj  of  Sec.  4,  whieh  reached  a  depth  of  1160  feet,  and  the 
Hidalgo,  in  the  NE]  of  Sec.  6,  with  a  depth  of  1925  feet.  No  paying 
oil  sand  was  encountered  in  any  of  these  wells,  although  light  showings 
of  oil  and  gas  were  reported.  The  Dabney  &  Roberts  well  demon- 
strates that  the  Sespe  is  about  400  feet  thick  on  the  axis  of  the  anticline 
and  that  the  Tejon  is  apparently  not  productive  along  this  portion  of 
the  fold. 

This  situation,  where  wells  along  the  axis  of  the  fold  fail  to  produce, 
while  wells  located  a  mile  down  the  flank  show  production,  is  a 
peculiar  one  for  California  fields.  The  only  explanation  that  the 
writer  can  offer  is  as  follows:  The  heavy  black  oil  produced  by  the 
Union  and  Scarab  wells  from  the  Sespe  beds  is  not  of  Eocene  origin, 
but  has  accumulated  in  the  upper  Sespe  sands  from  the  ^Monterey  shale 
which  overlies  the  Sespe  unconformably  a  short  distance  north  of  the 
Scarab  wells.  Apparently  the  oil  did  not  enter  the  lower  400  feet  of 
the  Sespe  which  covers  the  axis  of  the. fold.  In  this  connection  account 
must  also  be  taken  of  an  igneous  dike  which  outcrops  parallel  to  the 
axis  of  the  fold  about  one-half  mile  nortli  of  the  mouth  of  the  canyon. 
This  intrusion  may  have  prevented  the  oil  from  accumulating  in  sands 
along  the  axis.  The  reason  for  the  Tejon  being  apparently  unpro- 
ductive may  be  due  to  the  fact  that  the  quantity  of  oil  capable  of 
being  formed  by  the  jMeganos  shales  was  limited  and  has  collected  up 
the  plunge  of  the  axis  in  the  vicinity  of  Tapo  Canyon,  leaving  the 
remainder  of  the  fold  apparently  barren. 

It  must  be  noted,  however,  that  there  is  some  reason  to  believe  that 
the  wells  drilled  at  the  mouth  of  the  canyon  did  not  give  fair  tests  to 
the  siiowing  reported.  The  failure  of  these  wells  has  had  the  effect  of 
retarding  exploration  work  on  the  west  end  of  the  Simi  anticline. 

Unproven  Areas  in  the  Simi  Valley. 

The  south  side  of  the  valley,  from  Simi  to  Santa  Susana  Pass,  con- 
sists of  a  monocline  in  Avhich  the  Cretaceous,  ^lartinez,  Meganos  and 
Tejon  formations  are  exposed.     The  dip  is  about  25°  to  the  north.     The 
structure  may  be  considered  as  the  south  flank  of  the  Simi  syncline. 
The  Tejon  beds,  which  are  productive  on  the  north  side  of  the  valley, 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  125 

show  no  evidciiec  of  pi'lrolciiiii  lifrc  One  \\v\l  has  been  driUcd  in  this 
distrid.  that  of  the  Calabasas  Oil  Oonipany  in  the  NEj  of  Sec.  13, 
T.  2  X..  1\.  18  W.  The  well  starts  down  in  the  Te.ion  and  a  depth  of 
1900  feet  was  readied  witlioiit  ohtainino^  any  showing  of  oil,  altliongh 
gas  was  reported.  See.  ("1).  Fig.  7,  shows  the  general  structure  of  the 
valley  between  Moore  Park  and  Santa  Susana. 

The  north  side  of  the  valley  west  of  Moore  Park  and  Happy  Canyon 
is  known  as  the  Las  Pusas  district.  The  structure  consists  of  a  great 
syncline  between  South  ^Mountain  and  the  west  end  of  the  Simi  anti- 
cline. The  formation  exposed  on  the  surface  is  the  Fernando.  Along 
the  south  flank  of  South  ]\Iountain  it  is  underlayed  by  ^Monterey  shale 
which  is  bituminous  and  contains  burnt  shale  areas.  Within  the  gen- 
eral synclinal  structure  thei'e  are  at  least  two,  and  possibly  more,  minor 
anticlinal  folds.  The  most  prominent  of  these  is  found  about  3  miles 
north  of  Somis,  crossing  Sulphur  and  Long  canyons  at  approximately 
right  angles.  Tliis  fold  is  now  being  tested  by  the  Standard  Oil  Com- 
pany- on  the  Doidon  tract.  AVell  No.  1  was  drilled  to  depth  approxi- 
matel}'  2700  feet  and  abandoned  on  account  of  mechanical  diiTiculties; 
no  showings  were  encountered.  Well  No.  1-A  is  now  drilling.  In 
addition  the  following  wells  have  been  drilled  and  abandoned  in  this 
area  without  obtaining  anv  showings:  Tlu^  Honda  Oil  Company's  well 
in  tlie  SE]  of  Sec.  29,  T.  3  N.,  R.  20  W.,  was  located  on  the  north 
flank  of  the  great  syncline,  and  at  a  depth  of  1650  feet  went  out  of 
the  Fernando  into  the  underlying  IMonterey,  continuing  in  that  forma- 
tion to  a  depth  of  1875  feet.  This  well  demonstrated  that  the  Fernando 
on  the  south  flank  of  South  oMountain  is  not  productive.  The  Cali- 
fornia Profit  Sharing  Oil  Compan^y  drilled  a  well  about  one  mile  north 
of  ^Foore  Park  and  a  hundred  yards  east  of  the  Grimes  Canyon  road. 
A  depth  of  2410  feet  was  reached  in  the  Fernando. 

The  possibilities  that  the  Las  Posas  district  will  produee  are  not  very 
favorable.  That  is  due  chiefly  to  the  fact  that  the  structure  is  synclinal. 
The  snudl  minor  anticlines  noted  above,  one  of  which  is  being  tested 
by  the  Standard  Oil  Company,  are  apparently  only  surface  flexures 
in  the  upper  Fernando,  or  Saugus,  and  do  not  influence  the  accumula- 
tion  of  petroleum. 

West  End  of  the  Simi  Anticline. 

At  the  mouth  of  Brea  Canyon  the  Simi  anticline  crosses  the  valley 
to  the  south  side  and  contiiuies  westward  along  tlu'  top  of  the  range  of 
liilLs  between  iloore  Park  and  Somis.  In  the  Tierra  Kejada  district, 
south  of  Moore  Park,  the  formation  exposed  on  the  axis  is  Sespe,  with 
a  thin  covering  of  a  basaltic  lava  flow  which  is  characteristic  of  the 
base  of  the  ^Monterey  in  Simi  Valley  and  the  South  ^Fountain  areas. 
Further  west,  in  the  hills  near  Somis,  the  formations  consist  of  sands, 
clays  and  gravel  of  the  Fernando.  The  low  range  of  hills  west  of 
Somis  is  probably  a  continual  ion  of  TITe  fold,  though^  gQO^^  jjps -to 
prove  this  are  rare.  J.  B.  Dabney  drilled  a  well  here,  on  the  Perkins 
property,  about  ;:jThiles  west  of  Somis  and  a  mile  soutli  of  the  highway ; 
AP~oil  was  encountered^  From  the  log' it  is  evident  that  the  follo\ving 
format.ionsf  arp  present:  Fernando  to  about  1700  feet;  Monterey  sliale 


126  CALIFORNIA    STATE    MINING   BUREAU. 

and  Vaqueros  sandstone  from  ;ibont  1700  f(M't  to  2885  feet.  At  that 
point  lava  was  encTiunU'i-cd  and  the  well  aT)ai"uloned.  TTie  lava~proT)- 
ahly  represents  the  tlow  at  the  base  of  the  Monterey  series.  Thg., 
well  may  be  considered  as  showing  that  the  Fernando  and  Monterey 
are  not  prodnetive  along  the  lower  end  of  the  Siini  antirTTnl^'. "  AtTlie 
siinie  time  the  well  was  not  drilled  deep  enough  to  test  the" Sespe  and 
Tejon  which  are  probably  present  beneath  the  lava  eneonntered  at 
2885  feet.  The  general  possibilities  of  the  Simi  anticline,  west  of  Brea 
Canyon  may  be  snnnned  np  as  follows:  The  sti'iid  iii'c  is  fjuofiiltlo.  but 
wells  at  Bi'ca  ("an\on  have  demoiisti-ated  that  tlic  Srspc  and  IxJmi 
arc  not  productive  in  that  particular  rcj^ion.  aiul  the  Dabnej-  \veILat 
the  extreme  western  end  shows  likewise  that  the  Fernando  and  Monte- 
rey are  bari'en.^It  is,  howevei".  worthy  of  being  tcstc(i  i)y  a  well  located 
on  the  axis  in  the  area  south  of  Mooi'c  Pai'k  with  a  view  to  obtaining 
production  from  the  Tejon.  The  scci)agis  at  the  foot  of  Conejo  grade 
indicate  that  the  Tejon  is  oil  hearing  somcwiifrc  at  the  lower  end  of 
the  Simi  Vallev. 


District  Around  Oxnard,  El  Rio  and  Camarillo. 

The  area  is  fiat  and  covered  with  recent  soil.  There  are  no  surface 
indications  of  petroleum.  It,  however,  possesses  the  possibilities  com- 
mon to  flat  areas  adjoining  productive  fields,  that  it  possibly  may 
contain  buried  anticlinal  folds  of  which  there  is  no  evidence  on  the 
surface.  If  such  folds  are  present  they  Avonld,  in  all  probability,  be 
a  continuation  of  the  Sonth  ^fountain  fold  in  a  western  direction 
towards  El  Rio,  and  a  similar  exten.sion  of  the  Simi  anticline  towards 
Camarillo.  As  stated  before,  the  seei^agC-Of  iig]jl-gr.e£iL.oil_aJ:_t_he  fpoi 
of.  the  Cp^PJQ  .gJ^"«^.de,  indicates^  that.  tjie_  Eocene,  is_oil-iieaidngj.li  lliis 
portion  of  thecountVj. 

District  of  the  Santa  Monica  Mountains  Lying  in  Ventura  County. 

This  district  comprises  the  mountain  region  in  the  southeast  quarter 
of  the  county,  lying  south  of  the  Simi  Valley.  In  the  vicinity  of  Santa 
Susana  Pass  and  Chatsworth  Peak,  the  formation  is  Chico-Cretaceous, 
which  runs  west  in  a  continuous  botly  as  far  as  the  vicinity  of  Simi 
Piak.  Along  the  lower  Hank  of  the  Simi  Hills  this  body  of  Cretaceous 
is  overlayed  by  the  Martinez,  ]Meganos  and  Tejon.  The  general  dip 
of  these  formations  is  about  25°  to  the  north,  and  this  monocline 
represents  the  north  tiank  of  the  axis  of  an  anticline  which  was  once 
I)resent  just  south  of  Simi  Peak.  The  axis  has  been  faulted,  however, 
so  that  only  the  iiorth  Hank  and  plunging  nose  of  the  fold  are  left. 
The  strike  of  the  fault  is  approximately  east  and  west,  and  it  may 
l)e  seen  in  the  region  about  one-half  mile  south  of  Simi  Peak.  The 
plunge  of  the  faulted  fold  causes  the  strike  of  the  Eocene  formations 
along  the  north  tlank  to  ( hange  from  east-west  to  north-south,  so  that 
west  of  Simi  Peak  they  'nose  around'  over  the  Cretaceous,  and  they, 
in  turn,  give  place  to  th(>  Vacpieros  and  ^Monterey  in  the  region  just 
northeast  of  Newbury  Park.     The  fault  apparently  ends  about  a  mile 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  127 

west  of  Simi  Peak,  so  tluit  the  Monterey  Series  is  still  domed  and  the 
axis  of  the  fold  m:\y  \h-  reeowiiized  near  the  Cone.jo  Oil  Syndieate  well 
located  ahoiit  12  miles  northeast  of  Xewhiiry  Park. 

The  formations  exposed  south  of  the  Simi  Peak  fault  consist  of 
Vaqueros  sandstone  and  Monterey  shale.  These  continue  westward  to 
the  vicinity  of  Newbury  Park  and  the  Conejo  Valley,  and  east  to  the 
San  Fernando  Valley  in  the  vicinity  of  Calaliasas. 

Two  wells  are  being  drilled  in  this  general  vicinity  and  should 
detei-mine  the  possibility  of  this  region  as  they  are  favoral)ly  located 
on  the  plunging  nose  of  the  faulted  anticline.  Well  No.  1  of  the  Conejo 
Oil  Syndicate,  is  located  about  two  miles  northea.st  of  Newbury  Park 
and  starts  down  in  ^lonterey  shale,  which  is  dipping  about  45'  to  the 
west.  Well  No.  1.  "Hrhe,'"'  of  the  ("onejo  Oil  Syndicate,  is  located 
about  4  miles  noi'theast  of  Xewbury  Park,  and  starts  down  in  the 
Vacpieros  close  to  tlie  Tejon  contact.  The'structure  is  fairly  favorable 
and  the  region  is  underlaid  ])y  the  Tejon  and  ^NFeganos  which  are  oil- 
bearing  on  the  north  side  of  the  Simi  Valley.  However,  there  is  a  total 
lack  of  seeps  along  the  outcrops  of  these  beds,  such  as  are  common  in 
the  region  north  of  Simi  Valley.  It  would  seem  that  if  the  region  is 
oil-bearing  there  would  be  some  indication  of  oil  at  the  outcrops. 

In  the  hills  just  south  of  the  state  highway  and  Newbury  Park,  the 
formation  is  lava,  probably  belonging  to  the  Vaqueros.  From  these 
hills  south  to  the  coast  the  formations  consist  of  highly-tilted  areas  of 
Cretaceous  and  Eocene  age.  together  with  some  areas  of  ]\Iiocene  lava. 
The  region  may  l)e  considered  as  unfavorable  on  account  of  the  sharply- 
tilted  rocks  and  total  lack  of  any  surface  indications. 

At  the  foot  of  the  Conejo  grade,  about  3  miles  east  of  Camarillo, 
there  are  seeps  and  a  group  of  shallow  producing  wells.  This  is  known 
as  the  Conejo  field.  The  oil  has  apparently  collected  in  the  recent 
valley  alluvium  of  a  little  basin,  lying  between  two  areas  of  Vaqueros 
lava  flows.  The  oil  is  light-green  in  color  and  of  about  16°  Beaume 
gravity.  It  is  apparently  of  Eocene  origin.  It  has  no  gasolene  content 
and  is  practically  a  ])ure  lubricant,  indicating  that  it  has  migrated  a 
considerable  distance  and  has  been  filtered.  The  wells  are  drilled  in 
the  alluvium  to  depths  between  200  and  300  feet,  and  production  has 
been  obtained  here  for  the  last  twenty  years.  In  1919  there  were 
20  wells  i)roducing  with  a  total  daily  yield  of  17  barrels  of  oil  and  a 
hundred  or  more  of  water.  In  the  latter  part  of  1920  drilling  was 
started  again  after  a  ten-year  period  of  idleness,  and  the  new  wells  have 
come  in  with  an  initial  production  of  from  30  to  100  ])arrels  of  oil, 
followed  l)y  a  rapid  decline.  The  origin  and  method  of  accumulation 
of  the  oil  is  obscure ;  it  is  the  opinion  of  the  writer  that  it  was  formed 
in  the  Eocene  shales  and  has  migrated  along  a  fault  plane  up  through 
the  lava  and  into  the  alluvial  basin,  as  shown  in  Fig.  8,  lying  in  the 
basin  in  a  manner  similar  to  water  in  a  lake.  The  chief  interest  it 
has  is  in  demonstrating  that  there  is  Eocene  oil  at  the  lower  end  of  the 
county,  with  a  possible  accumulation  in  the  Tejon  at  the  west  end  of 
the  Simi  anticline. 


128 


CALIFORNIA    STATE   MINING   BUREAU. 


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NORTHWESTERN  LOS  ANGELES  COUNTY. 

This  area  comprises,  roughly,  the  territory  lying  north  of  San 
Fernando  Pass  and  west  of  the  Antelope  Valley. 

The  northern  portion  consists  of  the  Sierra  Liebre  ^Mountains,  over 
which  the  ridge  route  of  the  state  highway  passes.  The  central  portion 
consists  of  a  valley  area,  made  up  of  Soledad  Pass.  Xewhall  Creek  and 
the  Santa  Clara  River  Valley,  all  of  which  drain  westward  to  the  ocean 
through  Ventura  County.  The  southwest  corner  consists  of  the  Santa 
Susana  ^Mountains,  and  contains  the  proven  iields  of  the  district. 

The  eastern  portion  of  the  Sierra  Liebre  Range  is  composed  of  granite 
and  ancient  crystalline  schists.  The  western  Cjuarter  lying  between 
Castae  Creek  and  the  Ventura  County  line,  is  composed  of  sedimentary 
deposits.  These  beds  have  a  thickness  of  well  over  10.000  feet.  The 
lower  portion  consists  mainly  of  shales,  Avith  thin  beds  of  sandstone. 
The  upper  portion  consists  mainly  of  yellow-brown  medium  coarse 
sandstone,  with  some  minor  beds  of  shale  and  conglomerate.  They  are 
first  exposed  along  the  Ridge  Route,  about  six  miles  north  of  Castae 
Station,  and  the  general  dip  is  about  30"  to  the  north,  with  occasionally 
a  southward  dip.  The  beds  continue  as  far  north  along  the  Ricige 
Route  as  the  Liebre  maintenance  of  way  station,  at  Mhich  point  they 
are  sharply  faulted  against  the  granites  by  the  San  Andreas  fault. 
So  far  as  known,  they  contain  no  evidence  of  petroleum.  Their  age 
is  uncertain,  however,  they  are  ai)parently  continuous  with  the  Eocene 
beds  of  Ventura  Count}^  and  resemble  them  to  a  marked  degree  in 
lithology  and  may,  therefore,  be  assumed  to  belong  to  the  Topatopa 
Series. 

On  the  southern  flank  of  the  Sierra  Liebre  Range,  which  forms  the 
northern  boundary  of  the  Santa  Clara  River  and  Soledad  Canyon,  in 
the  region  north  of  Saugus,  the  Eocene  beds  above  referred  to  are  over- 
lain unconformably  by  the  Fernando.     These  Fernando  beds  consist 


PETROLEUM    RESOURCES  OF   CALIFORNIA.  1-0 

of  travels    white  and  yellow  saiulstotie  and  yellow  elay-shales.     They 
^/        1  nn  (S<tM,.    San  Franeisquito  and  Deadnian's  canyons  tor  a 

Xi^ri  at  W^ix  miw"on/the  point  whore  tl^se  canyc^s  join 
fleSantfckra  River.     Thev  are  also  continuous  up  Solecad  Pass  for 

a  diftan  '  of  atnit  10  nnles  east  of  Saugus.     Westward  from  Ca.tac 

]he  in  s°nnlar  beds  in  Ventura  County  in  the  region  nor  heast  of 
P  ru  The  region  contains  a  number  of  well  developed  folds  in  the 
Fernando  whk-h  n.ight  possibly  l>e  oil-bearnig.  A  --^^;^-:  .«  /^^^ 
abandoned  wells  drilled  here  have  reported  ^i^^^-^^f^^ut  faded  to 
ol)tain  anv  commercial  production.  In  view  of  this  the  area  may  be 
pousidered  as  one  of  doubtful  possibilities.  ^  -r.     ^  » 

Allowing  is  a  list  of  the  abandoned  wells,  taken  from  Prutzman  s 

Report  ■} 

"Wells  in  Townships  4-17.  north 

••East  Piru  Oil  Company-This  oompany  was  drilling    i^ 

of  Leckler  Canyon,  noar  Uie  center  of  Sec.  6.  .J^e  results  or  in  s  ^^        ^j 

"Aetna  Oil  Company-This  company  has  two  wels  on  ^he  h  .   -^^^^^oned  because 

Sec.  8.  drilled  about  1901.  Well  No  1  was  S45  feet  deep  ana  ^^a  ^^,^^g^_  ^  little 
?^  t^h^i'ru^tt.^^flKs^'^arrfoirorrt^l'^^vrfboi^^  and  was  abandoned 
as  a  dry  hole. 

"Wells  In  Townships  5-17  and  5-16. 

•■Cstalc  on  Company-TMS  well  was  drined  on  tl,|  j)"*  Ijif,"'  ^.^S^'SS-^^'!; 

zarfoio'v-irs:  sj/i^^s-r^'o'^Lif-.S' „,'^;;  sr.. « e.. .»»..  t„is  hoie 
"^°,^„3^Slf°^:;;inS■-rn7»f 'f.;.{9ipa",v/„Hi,ea  a  j^^^^^^^^ 

SEl'c']S.="SL"L;rae™S^°o.V'l\ir.'--a°"^^^  "»"  "-■'-  "•<""  "•» 

""•'•N?ew'Sa...lc  Oil  Company-Thj,  company  has  ';«",,;;f™;rS,  r°eU"rteYto  b"'',™™ 
l^oo'^^^e.  in°i  fSli;!|/w,?lT'a«  s.|nf  as    ?  «;,^^S^^^^^^ 

The  Rose  well  appears  to  have  been  almost  ex    ctly  «'   .^'^^^t  'f^e  suVface,  at  least,  has 
Castaic  well  is  some  distance  out  on  the  south  limb,  which  at  inc  buixdc  , 
a  sharp  dip." 

Following  is  a  list  of  the  wells  now  drilling  in  this  region,  none  of 
which   have   obtained   any   commercial   showing,   at   the   date   oi   tnis 

'' Wa\ker-Pearson  &  McGregor,  well  No.  1,  Sec  32  T.  4  N.,  R-  15  W., 
Communitv  Oil  Producers'  Company,  wells  No.  1  and  2  Sec.  2^,  i .  4  rj., 
R  16  W.,  Loma  Verde  Petroleum  Company,  well  No.  1,  Sec  ^.  i- *^-' 
R  17  W.,  Fernando  Oil  Company,  well  No.  1,  Sec.  10^  1.  4  ^•' ^- J-_'  ^•' 
Tick  Canyon  Oil  Syndicate,  well  No.  1,  Sec.  35  T.  5  N  R_  15  W^, 
Occidental  Petroleum  Company,  well  No.  1,  Sec.  35,  T  5  N.,  R.  16  W. 
The  eastern  portion  of  Soledad  Canyon  is  composed  of  granite  and 
crvstalline  schist,  together  with  smaller  areas  of  gravels,  sand  tutt 
beds  and  lava  tlows.     This  portion  of  the  canyon  is  unsuitable  tor 

^'^ThrreSn  south  of  Saugus,  known  as  the  Santa  Susana  Mountains, 
contains  the  proven  fields  of  this  portion  of  Los  Angeles  County. 
These  are  generally  known  as  the  Newhall  fields,  and  were  the  scene 

.California  State  Mining  Bureau.     Bull.  63.     Petroleum  in  Southern  California.     By 
Paul  W.  Prutzman,  1913. 
9—13322 


130  CALIFORNIA    STATE    MINING    BUREAU. 

of  some  of  the  first  development  work  in  California.  The  proven 
areas  t-onsist  of  a  numher  of  isolated  i^roups  loeated  at  the  heads  of 
Pieo,  Towsley,  Wiley  and  Riee  canyons.  '  These  wells  are  located  along 
the  axis  of  a  sharp  northwest-southeast  fold,  known  as  the  Pico  anti- 
cline. The  wells  ai)parently  start  down  in  the  Fernando  and  draw' 
their  oil  from  sandstone  beds  in  the  Monterey  Series.  These  groups 
of  wells  lie  west  of  Newhall.  In  Pico  Canyon,  on  the  property  of  the 
Standard  Oil  Company,  is  loeated  the  first  producing  well  obtained  in 
California.  This  well  was  drilled  in  1870  and  is  still  producing  at  the 
rate  of  3  barrels  per  day  of  38"  gravity  oil.  At  tlie  head  of  San 
Fernando  Pass,  and  in  the  hills  southeast  of  Xewhall,  are  located  the 
Elsmere  Canyon  wells.  The  formation  here  consists  of  Fernando, 
which  is  lying  unconformably  upon  tKe  granite.  The  oil  is  found  in 
the  basal  sands  of  the  Fernando  and  is  of  a  heavy  gravity,  ranging 
from  14°  to  19°  Baume.  This  is  in  marked  contrast  to  the  Pico  Canyon 
wells  Avhich  run  over  30^  Baume  in  gravity.  The  structure  consists 
of  several  sharp  anticlines.  In  Placerita  Canyon  some  oil  has  been 
found  in  an  area  of  cry.stalline  schist,  having  migrated  there  from 
the  Fernando.  This  is  a  freak  occurrence  and  was  referred  to  in 
Chapter  II. 

The  general  depth  of  wells  in  the  Xewhall  area  ranges  from  1000  to 
2000  feet.  The  oil  has  prol)ably  had  its  origin  in  the  shales  of  the 
^Monterey  Series,  and  has  collected  in  the  Vaqueros  sandstone  and 
overlying  Fernando  beds.  The  total  proven  area  in  ^Farch,  1921,  was 
205  acres.  The  total  daily  average  production,  in  December,  1920,  was 
308  Ijarrels  of  oil.  The  average  number  of  wells  producing  was  77, 
with  an  average  daily  production,  per  well,  of  4.0  barrels  of  oil  and  1.2 
of  water.  The  limits  of  the  proven  areas  are  practically  set  and  it  is 
doubtful  if  the  pi'oduction  can  he  increased  any  in  the  future. 


PETROLEUM    RE^^OURCES   OF    CALIFORNIA.  I'^l 

CHAPTKR  X. 
Southern  Los  Angelks  and  Orange  County. 

This  area  iudiules  all  of  Orancr,-  County,  and  that  portion  of  Los 
An-.les  (\,nntv  Ivin-  soutli  of  the  San  F.rnanao  Pass  and  the  San 
Gabriel  .Mountains.  This  is  the  cliief  produem-  area  of  Southern 
California,  and  the  seeond  in  the  state.  Li  this  report  no  detailed 
descriptions  will  be  given  of  the  proven  areas,  and  the  reader  is 
referred  to  tlie  bulletins  of  the  (ieolo-ieal  Survey^  and  the  State  .Aiming 
Bureau,-  for  this  information. 

POSSIBILITIES   OF   THE  VARIOUS   DISTRICTS. 

Santa    Monica    Mountains. 

The  Santa  :\ronica  :\rountains  lie  in  the  extreme  southwestern  por- 
tion of  Los  Alleles  (\)untv,  and  continue  west  into  Ventura  County. 
Thev  offer  no  indiuement  for  drilling  operations.     The  general  geology 
is  as  follows:  Beginning  at  a  point  on  the  Los  Angeles  River  north  ot 
Elysian    Park  and  running  westward  is  a  body  of  crystalline  rocks, 
chietlv  granite  gniesses  and  schists,  which  form  the  core  of  the  range. 
Alon."'    the    north    Hank,    and    bordering   the    south    side    of    the    San 
Fernando  Vallcv.  the  crvstalline  rocks  are  overlay. 'd  by  the  Monterey 
Series,  consisting  of  white  Vaciueros  sandstone  and  diatomaceous  Mon- 
terey shale.     The  structure  is  that  of  a  monocline,  dipping  about  -iU    to 
the  north       This  bodv  of  sediments  is  continuous  from  Cahuenga  Pass  to 
Calal)asas,  where  it  joints  the  :\Ionterey  Series  along  the  Conejo  Grade. 
On  the  south  Hank  of  the  range  from  Elysian  Park  to  Sherman    the 
crvstalline  core  is  overlayed  at  the  edge  of  the  foothills  l)y  the  Mon- 
terev  Series  and  the  Fernando.     These  l)eds  dip  to  the  south  and  torm 
the  Los  Angeles  Citv  and  Salt  Lake  fields  which  lie  out  in  the  flat  area 
about  two   miles  south   of   the   mountains.     In   tlie   hills  back  ot  the 
Soldiers'  Home  at  Sawtelle,  the  formations  exposed  are  beds  ot  sand- 
stone   and    shale,    probably    belonging    to    the    lower    portion    ot    the 
Monterey  Series   (locallv  known  as  the  Puente).     These  beds  are    m 
turn    imderlaved  bv  the  Chico  (Cretaceous),  which  occupies  a  wedge- 
shaped  area,  that  gradually  widens  towards  Topango  (^anyon.     Along 
the  Topango  Canvon  road  the  Chico  consists  of  massive  sandstone  and 
coarse  coiiolomerate,  with  minor  beds  of  shale.     These  beds  are  highly- 
tilted  and"have  a  general  dip  to  the  north.     Ah.ng  the  beach  from 
Santa  Monica  Canvon  to  Topango  Canyon  the  lower  Puente  CMonterey) 
is    overlaid    bv    bituminous    shale    probably    l)elonging    to    the    upper 
Puente  (.Monterey).     The  shale  is  exposed  along  the  sea  cliff  and  the 
total  thickness  is  iiot  over  a  few  hundred  feet. 

n\   S.    Geological   Survey.     Bull.    .309.      Santa   Clara   Valley    Puente    Hills   and    Los 
Ansele.s  Oil  Di.slritt.      Bv  G.  H.  Eldridse  and  Ralph  Arnold,  190  <. 

^California  State  Mining  Bureau.      Bull  63.      Pf '•ol^,'?  '"  J""^'^^^"  r^  p^Tc^iauSi^- 
P   W    Prutzman,  1913.     Bull.  69.     Petroleum  Industry  of  California      By  R.  P.  Mti^augli 
lin   and   C    A.   Waring.    1914.      First,   Second   and   Third   Annual    Repots   ot    the   btae 
Oil   and   Gas   Supervisor.      Summary   of   Operations,   California   O.l   Fields.      Report  on 
the  Montebello  Field.      By  Irving  V.  Augur.      May,  1920. 


132  CALIFORNIA   STATE   MINING   BUREAU. 

The  o-onlopfv  of  the  Santa  IMoniea  Mountains  is  ehiefly  interesting 
because  of  the  outcrops  of  IMonterey  shale  along  its  borders.  The  out- 
crops on  the  northern  flank  indicate  that  the  San  Fernando  Valley  is 
underlaid  by  the  INFonterey,  and  those  on  the  .southern  border  and 
along  the  coast  indicate  similar  conditions  in  the  region  between  Los 
Angeles  and  Santa  IMonica. 

San   Fernando  Valley   District. 

The  San  Fernando  Valley  consists  of  a  flat,  oblong  area,  completely 
surrounded  by  mountains  except  for  the  narrow  pass  at  the  southeast 
corner  between  the  Verdugo  and  Santa  ^Fonica  mountains,  through 
which  the  drainage  flows  by  means  of  the  Los  Angeles  River. 

The  fiat  valley  area  is  covered  with  soil  and  recent  valley  deposits 
which  give  no  hint  as  to  the  underlying  formation.  The  one  exception 
to  this  consists  of  an  area  of  crystalline  rocks  and  Vaqueros  sandstone 
which  outcrops  in  the  small  group  of  isolated  hills  just  east  of  Pacoima. 

The  geology  of  the  foothills  suri'ounding  the  valley  is  as  follows: 
Along  the  southern  edge  from  Cahuenga  Pass  to  Calabasas,  the  forma- 
tions consist  of  Vaqueros  sandstone  and  ^NFonterey  shale,  dipping  in  a 
monocline  to  the  north.  From  Cahuenga  Pass,  east  to  "West  Glendale, 
there  is  some  ^Monterey,  but  the  main  formations  consist  of  granite  and 
schist. 

At  the  southwestern  head  of  the  valley,  in  the  vicinity  of  Calabasas 
and  south  of  Chatsworth,  the  beds  exposed  are  Vaqueros  sandstone  and 
^NFonterey  shale.  At  Chatsworth,  and  in  the  vicinity  of  Santa  Susana 
Pass,  massive  Chico  sandstone  outcrops.  In  the  hills  iiorth  of  Chats- 
worth and  west  of  San  Fernando,  Monterey  shale  and  Fernando  sands, 
clays  and  gravels  are  exposed.  This  region  contains  the  most  favorable 
structures  in  the  valley  for  the  accumulation  of  oil.  One  of  these  anti- 
clines starts  in  the  hills  between  Limekiln  and  Aliso  canyons  and  runs 
out  into  the  valley  in  a  southeast  direction,  terminating  in  the  low 
group  of  hills  two  miles  south  of  the  San  Fernando  Mission.  The 
second  fold  runs  east  and  west  in  the  hills  that  surround  the  San 
Fernando  reservoir.  The  axis  of  the  anticline  passes  approximately 
along  the  face  of  the  dam  at  the  southern  end  of  the  reservoir  and 
continues  east  towards  San  Fernando  for  about  a  mile,  and  west  as 
far  as  Aliso  Canyon.  These  two  folds  are  now  being  tested  by  the 
'Mission  Wells'  of  the  Standard  Oil  Company,  and  while  depths  of 
4000  feet  and  over  have  been  reached,  no  encouraging  results  have 
been  obtained.  The  final  results  obtained  by  these  wells  should  prove 
or  disprove  the  oil  possibilities  of  the  valley. 

The  San  Fernando  Oil  and  Gas  ('ompany  is  drilling  a  well  about  a 
mile  north  of  the  reservoir  dam,  a  location  too  far  north  of  the  axis 
of  the  fold  to  be  an  adequate  test  of  the  region.  The  northwest  head 
of  the  valley,  in  the  vicinity  of  San  Fernando  Pass,  may  be  considered 
as  a  continuation  of  the  Elsmere  Canyon  structure  (discussed  in 
Chapter  IX).  It  is  possible  that  in  the  vicinity  of  Grapevine  Can3^on, 
on  a  continuation  of  the  Elsmere  Canyon  fold,  small  Avells  of  heavy 
oil  and  doubtful  commercial  value  may  be  obtained.  The  Active  Oil 
Company  is  drilling  a  well  at  the  mouth  of  Grapevine  Canyon. 

In  the  hills  northeast  of  San  Fernando,  between  Pacoima  Wash  and 
the  Little   Tujunga,   the   formation   consists   of   j\Ionterey   shale   and 


Montebello  Iield,  Los  Angeles  County  (Looking 


nty  (Looking  West  Along   the  Axis  of  the  Fold). 


PETROLEUM    RESOURCES   OF   CALIFORNIA,  133 

Fernando  sands  and  frravels.  The  Monterey  is  exposed  in  a  narrow 
strip  running  east  and  west  at  the  edge  of  tlie  hills.  Between  Lopez 
Canyon  and  Pacoinia  Wash  there  are  several  seepages  and  the  shale  is 
bitnminized.  Overlying  the  shale  are  the  Fernando  beds.  The  dip 
of  both  formations' is  about  45'  to  the  north.  Two  wells  have  been 
drilled  at  the  edge  of  the  hills  and  just  east  of  Lopez  Canyon.  The 
Crafton  well  was  drilled  some  years  ago  and  encountered  small  quan- 
tities of  heavy  oil.  The  San  Fernando  Oil  Company  well  is  at  present 
testing  the  region  and  lias  to  date  encountered  only  small  showings  of 
heavy  tar.  At  the  month  of  the  Tujunga  Valley  there  are  outcrops  of 
Vaqueros  sandstone,  ]\Ionterey  shale  and  Fernando,  which  lie  on  the 
ci-ystalline  rocks  of  the  A'erdugo  ^Mountains  to  the  south,  and  the  main 
San  Gabriel  Range  to  the  north.  In  the  region  consisting  of  the 
Verdugo  ^Mountains,  La  Canada,  La  Crescenta,  Verdugo  Canyon,  the 
San  Rafael  Hills  and  P^agle  Rock  Valley,  the  possibilities  of  obtaining 
oil  are  extremely  slight.  The  greater  portion  of  the  region  is  covered 
witli  crystalline  rock  and  only  small  patches  of  sedimentary  rocks  are 
present.     Any  drilling  here  would  be  a  waste  of  money. 

The  Coastal   Plane  Area  of  Los  Angeles  and  Orange  Counties. 

Roughly,  this  region  may  be  defined  as  lying  between  Santa  Monica 
and  Newport  and  south  of  the  Santa  Monica  Mountains  and  the  San 
Gabriel  Valley.  Within  it  are  located  the  chief  proven  fields  of 
southern  California  and  it  also  offers  the  most  favorable  opportunities 
for  future  development. 

The  proven  fields  lie  roughly  along  three  parallel  lines  of  structure 
which  have  a  general  northwest-southeast  trend.  These  lines  of  struc- 
ture consist  of  a  series  of  donx^s,  anticlines  and  faults  along  which  the 
oil  has  accunudated.  These  arc  not  in  any  sense  absolutely  continuous, 
but  are  apparently  arranged  along  these  three  general  parallel  lines. 

The  first  and  most  northerly  of  these  begins  at  the  Salt  Lake  field, 
near  Hollywood,  and  runs  east  to  the  Los  Angeles  City  field  and 
thence  southeast  through  the  ^Montebello,  Whittier  Hills,  Brea  Canyon 
and  Olinda  fields.  The  second  line  of  structure  lies  about  three  miles 
south  and  parallel  to  the  first  and  is  separated  from  it  by  a  narrow 
syncline.  Beginning  at  the  southeast  this  general  structure  starts  in 
the  Richfield  district  and  runs  northwest  to  the  Coyote  Hills  field  and 
thence  to  the  Santa  Fe  Spring  area,  beyond  which  it  has  not,  to  date, 
been  identified. 

The  third  and  last  line  is  apparently  the  longest  in  extent,  and  is 
separated  from  the  second  by  a  broad,  flat  area  of  about  twelve  miles 
in  width  which  is  apparently  a  syncline  but  which  might  contain 
buried  folds.  Beginning  at  the  southeast,  this  general  line  of  structure 
starts  in  the  semi-proven  area  at  Newport  and  runs  thence  northwest 
to  the  Huntington  Beach  field  and  thence  to  the  Signal  Hill  dome.  At 
this  point  the  strike  changes  more  to  the  north  and  the  general  line  of 
uplift  continues  through  Dominguez,  Athens  on  the  Hill,  Inglewood, 
Culver  City  (Ivy)  and  finally  ends  in  the  proven  area  around  the 
Wolfskin  lease  of  the  West  Coast  Oil  Company  about  one  mile  southwest 
of  Beverly.  Sec.  A.  B.,  Fig.  9,  shows  the  general  relationship  of  these 
three  lines  of  structure. 


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CALIFORNIA    .STATE    MINING   BUREAU. 


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PETROLEUM    RESOURCES   OF    CALIFORNIA.  135 

Following  is  a  brief  clescription  of  tlie  fields  that  lie  along  the  first 
and  most  northerly  line  of  strueture : 

Salt  Lake  Field. 

The  Salt  Lake  field  lies  at  the  western  ond  and  (-(miprises  the  proven 
area  sonth  of  Sherman  and  Hollywood.  The  oil  is  fonnd  in  sandstone 
beds  of  the  Puentf  formations  and  vai-ies  from  11-  to  18'  Banme  in 
gravity.  As  there  are  no  surface  outcrops,  the  exact  structure  is  some- 
what obscure.  It  is  probable,  however,  that  the  accumulation  is  due 
to  a  major  anticline  which  runs  east  to  west  just  south  of  Colegrove 
and  Sherman.  Tliis  sti-ucture.  however,  has  ))een  faulted  on  both  Hanks 
and  contains  minor  folds  witliin  it.  Sec.  3,  Fig.  3,  shows  a  portion 
of  the  south  faulted  tiauk.  The  limits  of  the  field  are  practically  set. 
There  is,  however,  a  chance  to  encounter  deeper  sands,  as  shown  by 
recent  work  on  property  of  the  Salt  Lake  Oil  Company.  The  total 
proven  area  in  .March,  1921,  was  904  acres.  The  total  average  daily 
production  in  December,  1920,  was  2240  barrels  of  oil.  The  average 
number  of  i)roducing  wells  was  250,  with  a  daily  average  production, 
])er  well,  of  9  barrels  of  oil  and  10  of  water. 

Los   Angeles   City    Field. 

The  Los  Angeles  City  fields  lie  in  the  region  between  West  Lake  Park 
and  Elysian  Park.  Drilling  was  first  started  hci-e  in  1(S92  by  E.  L. 
Doheny,  and  the  area  was  the  scene  of  extensive  drilling  oj)erations 
up  to  about  1907.  Since  then,  however,  there  has  been  practically  no 
development  work.  This  is  due  mainly  to  the  exhaustion  of  the  oil 
sands,  and  the  restriction  placed  upon  the  drilling  of  new  wells  within 
the  city  limits.  At  the  present  time  about  400  of  the  old  Avells  are 
still  pumping,  and  the  total  daily  production  averages  about  1000 
barrels.  The  structui-c  consists  of  a  series  of  snudl  folds  and  faults 
in  the  Puente  formation.  The  majority  of  the  wells  start  down  in  the 
Fernando,  but  draw  their  production  from  the  sandstone  beds  of  the 
Puente.  The  oil  varies  from  11°  to  18  Baume  in  gravity.  The  field 
has  at  all  times  been  characterized  by  shallow  wells  and  small  produc- 
tion, and  it  is  pi'obable  that  the  next  few  years  will  see  the  abandon- 
ment of  the  remaining  producing  wells. 

The   Montebello   Field. 

The  next  field  that  lies  along  this  line  of  structure  is  the  ^Montebello 
field  which  is  located  in  the  La  Merced  llilis  about  six  miles  east  of 
Los  Angeles.  The  structure  consists  of  a  well  developed  dome  in  the 
Fernando  formation,  and  the  oil  is  found  in  the  basal  sands  of  this 
formation,  and  ])ossibly  in  the  up[)ermost  sands  of  the  Puente.  The 
limits  of  the  field  have  practically  been  defined  by  drilling,  and  no 
extension  is  looked  for.  There  is.  however,  still  considerable  room 
within  the  proven  limits  to  drill  up.  This  field  has  been  one  of  the 
most  prolific  in  Southern  (California,  but  it  can  l)e  considered  as  having 
passed  the  day  of  fiush  production.  The  total  proven  area  in  ]\Iarch, 
1921,  was  819  acres.  The  total  daily  average  production  in  December, 
1920,  was  30,000  barrels  of  oil.  The  total  number  of  wells  producing 
was  133,  with  a  daily  average  yield,  per  well,  of  240  barrels  of  oil 


136  CALIFORNIA    STATE   MINING   BUREAU. 

and  19  of  water.     For  a  detailed  description  of  the  field,  the  reader  is 
referred  to  a  report  by  Angur.^ 

In  the  region  lying  between  Montebello,  East  Los  Angeles  and  South 
Pasadena  there  is  a  series  of  low  rolling  hills  in  which  there  are  folds 
in  the  Pnente  formation.  In  the  little  gully  .iust  southeast  of  the 
County  Hospital,  there  are  several  seepages  in  what  is  apparently  the 
basal  sands  of  the  Pnente.  From  tliis  it  would  appear  that  this  region 
has  some  possibilities.  However,  two  wells  drilled  in  See.  25,  T.  1  S., 
R.  13  W.,  failed  to  obtain  production.  These  wells  were  the  'Hunting- 
ton wells'  of  the  Amalgamated  Oil  Company,  and  were  located  on  the 
axis  of  a  small  fold  just  east  of  East  Lake  Park.  The  depths  reached 
in  lioth  wells  were  approximately  3700  feet.  It  is  probable  that  the 
failure  to  obtain  oil  is  due  to  a  lack  of  reservoir  formations  above  the 
Puente.  This  genera]  region,  however,  may  be  considered  as  worthy 
of  further  examination  before  being  condemned. 

Whittier,  Brea  Canyon,  and  Olinda  Fields. 

Across  the  San  Gabriel  River  from  the  IMontebello  field  lie  the 
Puente  Hills,  and  along  the  southern  edge  of  these  hills  are  located 
a  series  of  proven  areas.  These  consist  of  the  Whittier,  Brea  Canyon 
and  Olinda  fields.  The  method  of  accunuilation  and  origin  of  the  oil 
is  practically  the  same  in  all  of  these  fields,  the  diatomaceous  shale 
of  the  Puente  (^Monterey)  l)eing  the  original  source  of  the  oil  which 
has  gathered,  either  in  sandstone  beds  of  this  formation,  or  in  the 
basal  sands  of  the  Fernando.  The  structures  along  which  the  oil  has 
accunuilated  consist  of  a  series  of  small  folds  in  the  Fernando  and  a 
number  of  faults  along  the  contact  of  the  Fernando  and  the  Puente. 
All  of  these  fields  ha-'e  passed  the  flush  day  of  their  production  and 
their  limits  are  practically  set.  In  ]\Iareh,  1921,  the  total  proven 
acreage  in  this  region  was  550  acres  in  the  Whittier  field  and  2073 
in  the  Brea  Canyon-Olinda  district.  In  December,  1920,  the  total  daily 
average  production  in  the  Whittier  field  was  2768  barrels  of  oil.  The 
average  number  of  wells  producing  was  173,  with  a  daily  average  yield 
j)er  well  of  16  barrels  of  oil  and  21  of  water.  During  the  same  period 
the  total  daily  average  production  in  the  Brea  Canyon-Olinda  district 
was  17.756  barrels  of  oil.  The  average  number  of  producing  wells 
was  372,  Avith  an  average  daily  yield  per  well  of  47  barrel;^  of  oil 
and  10  of  water. 

Richfield   District. 

Fields  along  the  second  line  of  structure  are  as  follows :  At  the 
eastern  end  along  the  Santa  Ana  River,  is  found  the  Richfield  district. 
There  are  two,  and  possibly  three,  separate  structures  in  this  area. 
These  consist  of  a  very  sharp,  short  anticline  along  the  west  bank  of  the 
Santa  Ana  River,  on  which  are  located  the  wells  of  the  Fullerton  Oil 
Company  and  the  Kraemer  No.  1  lease  wells  of  the  Standard  Oil  Com- 
pany. The  extreme,  sharp  pitch  of  the  flank,  and  the  westward  plunge 
of  the  anticline,  limits  the  productive  area  to  a  narrow  strip  along 
the  highest  point  of  tlic  fold.     The  axis  is  apparently  not  productive 

'California  State  Mining  Bureau.  Summar>-  of  Operations  California  Oil  Fields. 
Vol.  5,  No.  11.      May,  1920.      Report  on  tlie  Montebello  Field.      By  Irving  V.  Augur. 


ETROLEUM    RESOURCES   OF    CALIFORNIA. 


137 


11  No.  1  of  the  Standard  Oil  Company.     Drilling  to 
at   tlio  eastward  portion  of  the  strnoture  is  the  most 


is  a  low  group  of  hills  which  indicates  there  is  a  productive  structure 
underground.     Outside  of  these  hills  there  is  no  surface  evidence  of 


Biohfleld  Field,  On 


chfield  Field,  Orange  County. 


136  CALIFORNIA    STATE    MINING   BUREAU. 

and  19  of  water.     For  a  detailed  deseription  of  the  field,  the  reader  is 
referred  to  a  report  by  Aiigiir.^ 

In  the  region  lying  between  Montebello,  East  T^ns  Ano-ai-^  — j  -^     •■• 
Pasadena  n.^v/^  ^^  -  -  *^ 

in   th 
Conni 
basal 
has  s( 
R.  13 
ton  W' 
axis  0 
in  hot 
failnrt 
Puenti 
of  furl 

Whittle 

Acre 
Piiente 
a  series 
and  01 
is  prae 
of  the 
has  ga1 
basal  Sc 
aecunni 
number 
All  of  1 
their   li 
acreage 
in  the  B 
average 
average 
per  well 
the  total 
was  ITj 
was  372, 
and  10  0 

Richfield    I 

Fields 
eastern  e 
There  ar 
These  con 
Santa  An 
Company 
pany.     Tl 
of  the  an 
the  highef^ 

'Ciiliforni: 
\vL  5,  No.  1  -    - p-    ••  rMigur. 


PETROLEUM    RESOURCES   OF   CALIFORNIA.  137 

much  beyond  well  No.  1  of  the  Standard  Oil  Company.  Drilling  to 
date  indicates  that  tlie  eastward  portion  of  the  structure  is  the  most 
favorable. 

The  second  structure  consists  of  the  broad  anticline  on  which  the  main 
field  is  located.  There  is  no  surface  evidence  as  to  where  the  axis  of  this 
fold  is  located,  but  a  study  of  the  well  logs  indicates  that  it  runs  west- 
ward from  Amalgamated  Oil  Coinj^any  well  No.  1  to  Union  Oil  Company 
'Towell  No.  2,  and  thence  through  Petroleum  ]\Iidway  wells  No.  7  and 
No.  6  and  thence  through  the  T^nion  Oil  Company's  wells  'Coyle'  No.  1 
and  No.  3,  and  'Chapman'  No.  1  and  No.  12.  From  a  point  near  'Coyle' 
No.  1  there  is  a  westward  plunge  to  the  axis.  Wells  along  the  axis  vary- 
in  depth  from  2900  to  3100  feet,  and  in  some  cases  as  much  as  1000  feet 
of  oil  sands  are  open  to  production.  The  oil  is  apparently  found  in 
sandstone  beds  of  the  Pnente  formation.  Definite  evidence  as  to  this 
is,  however,  still  lacking.  This  portion  of  the  field  is  still  in  its  flush 
production,  and  the  limits  of  the  proven  areas  are  not  yet  determined. 
It  is  po.ssible  that  future  drilling  will  ext(^nd  the  field  considerably. 

About  one-half  mile  southeast  of  this  main  productive  area  is  a  group 
of  wells  located  around  the  Richfield  Consolidated  property.  Produc- 
tion has  been  encountered  here  at  about  2800  feet,  and  this  productive 
sand  apparently  cannot  be  correlated  witli  the  sands  of  the  region  to 
the  north.  AVhether  there  is  a  buried  fold  located  here,  or  whether  the 
sand  encountered  belongs  to  a  zone  that  was  passed  up  in  the  main 
field,  cannot  be  told  from  the  meager  data  that  is  at  present  available. 
In  INFarch.  1921,  the  total  proven  area  in  the  Richfield  district  was  800 
acres.  The  total  daily  average  production  in  December,  1920,  was 
15,360  barrels  of  oil.  The  average  number  of  wells  producing  was  60, 
with  an  average  daily  yield,  per  well,  of  256  barrels  of  oil  and  13 
of  water. 

Coyote    Hills    Field. 

Lying  about  2  miles  northeast  of  Richfield  is  the  Coyote  Hills  field. 
This  consists  of  a  series  of  anticlinal  domes,  apparently  three  in 
number.  The  first  of  these  domes  is  in  the  vicinity  of  the  Graham 
&  Loftus  lease  of  the  Union  Oil  Company;  the  second  is  located  in 
the  vicinity  of  the  'Ilualde'  lease  of  the  Amalgamated  Oil  Company; 
and  the  third  consists  of  the  famous  dome  structure  on  which  the 
'Murphy'  and  'Emery'  leases  of  the  Standard  Oil  Company  are 
located.  This  last  structure  has  been  one  of  the  most  prolific  areas  in 
Southern  California.  The  limits  of  the  Coyote  Hills  field  have  been 
practically  fixed,  and  the  day  of  flush  production  is  over.  In  ^March, 
1921,  the  total  proven  area  was  1885  acres.  The  total  daily  average 
production  in  December,  1920,  was  24,309  barrels  of  oil.  The  average 
number  of  wells  producing  was  219,  with  a  daily  average  yield,  per 
well,  of  111  barrels  of  oil  and  25  of  water. 

Santa   Fe  Springs   District. 

Westward  from  the  'Emery'  lea.se  of  the  Standard  Oil  Company, 
the  dome  structure  plunges  and  is  buried  for  a  distance  of  about  4 
miles,  emerging  again  in  the  Santa  Fe  Springs  area.  At  this  point  there 
is  a  low  group  of  hills  which  indicates  there  is  a  productive  structure 
underground.     Outside  of  these  hills  there  is  no  surface  evidence  of 


138  CALIFORNIA    STATE    MINING   BUREAU. 

the  iinderiiToiiiid  structure.  At  the  date  of  this  re])ort  only  one  pro- 
ducing well  has  been  obtained  in  the  Santa  Fe  Springs  field — the 
']\reyer'  well  of  the  T'nion  Oil  Company.  This  well  lias  been  pro- 
ducing for  two  years  light-gravity  oil  at  approximately  a  hundred- 
barrel  rate  from  below  a  depth  of  4000  feet.  There  is  no  evidence 
available  as  to  what  the  structure  consists  of.  It  is  probable,  however, 
that  it  is  an  antit-linal  fitld,  with  a  northwest-southeast  trend,  antl 
probably  passes  just  north  of  Santa  Fe  Springs.  The  extent  and 
productiveness  of  this  field  can  only  be  determined  by  actual  drilling. 

Newport  District. 

The  fields  along  the  third  and  most  southerly  structure  are  as  follows: 
At  the  extreme  southwestern  end  is  found  the  semi-proven  area  of  the 
Newport  district.  To  date  no  wells  of  conniiercial  value  have  been 
obtained  here,  and  it  is  doubtful  whether  any  better  results  will  be 
obtained  in  the  future.  The  structure  consists  in  general  of  a  mono- 
cline dipping  to  the  northwest.  The  formations  exposed  consist  of 
diatomaceous  shale  and  sandstone  of  the  Monterey  Series,  which  rest  on 
sandstone  beds  prohablx-  of  Koccne  age  in  the  San  .loa(piin  Hills,  and 
are,  in  turn,  overlaycd  b\-  IMiocenc  beds  in  the  area  west  of  Newport 
Bay.  The  .Monterey  shale  is  ap])arently  the  source  of  the  oil  which 
has  collected  in  sandstone  beds  of  this  formation.  There  are  several 
outcrops  of  tar  sand  along  the  road  on  the  east  side  of  Newport  Bay. 
Approximately  10  wells  have  bi^cn  drilled  in  this  area,  nearly  all  of 
which  have  eneou.ntered  heavy  tar,  but  have  been  unable  to  produce 
on  a  commercial  scale.  This  is  probably  due  to  the  unfavorable  mono- 
cline structure.  However,  in  one  portion  of  the  field  there  is  a  rather 
poorly  developed  anticline,  this  being  due  to  a  slight  doming  of  the 
Monterey  shale  beds.  The  axis  of  this  fold  runs  approximately  east 
and  west,  and  lies  half-way  between  the  Liberty  Petroleum  Company's 
well  No.  1  and  the  Interstate  Oil  Company's  well  'Irvine'  No.  1.  If 
any  further  development  work  is  undertaken,  a  location  on  the  axis  of 
this  structure  would  l)e  the  most  favorable  position  for  a  well  to  test 
out  the  district. 

Huntington    Beach   Field. 

Seven  miles  northwest  of  Newport  lies  the  newly  discovered  ITunt- 
ingt(m  Beach  fi(>ld.  This  field  centers  around  the  town  of  Huntington 
Beach,  and  a  group  of  low  hills  just  northeast  of  the  town,  known  as 
Las  Bolsas.  The  only  surface  evidence  of  an  oil  field  consists  of  these 
low  hills,  which  serve  as  a  topographic  expression  of  the  underground 
structure  and  gas  found  in  shallow  wells  on  the  property  of  the  Bolsa 
Chica  (iun  Club.  The  limits  and  structui'e  of  this  field  can  only  be 
determined  by  drilling.  From  such  data  as  is  available  to  date  it  is 
probable  that  the  structure  consists  of  an  anticlinal  dome,  with  a  north- 
west-southeast trend.  Drilling  has  been  almost  entirely  confined  to 
the  northeast  fiank  of  this  supposed  anticline,  so  that  tlie  location  of 
the  axis  is  still  undetermined.  However,  it  is  probable  that  it  runs  in 
a  northwest-southeast  direction  a  few  hundred  yards  west  of  'Bolsa 
Chica'  well  No.  1  and  'Huntington'  No.  2-A  of  the  Standard  Oil 
Company.     From  the  vicinity  of  Huntington  2-A  it  curves  towards  the 


PETROLEUM    RESOURCES   OF    CALIFORNIA. 


139 


HUNTINGTON  BEACH  FIELD,  OltANGE  COUNTY   (LOOKING  SOUTHEAST  ALONG  THE  AXIS  OF  THE  FOLD  FROM  THE  BOLSA  CHICA  LEASE  OF  THE  STANDARD  OIL  COMPANY). 


13322 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  139 

WiK'h  in  a  southeast  direction,  so  that  it  T>aS'Ses  throuirh  well  No.  1  of 
the  ninitiniiton  rentrnl  Oil  ('ninpaiiy  and  well  Xo.  1  of  tlie  TTurst  Oil 
(,'onipany,  and  slightly  east  ol"  well  .Xo.  ]  of  tlie  Pantaj?es  Oil  Company. 
From  this  point  sontlieast  its  location  is  not  known.  Northwest  of 
Bolsa  Cliiea  No.  1  the  strnctnre  a|)i)arently  plnny:es  sharply  to  the 
northwest.  'Toi'i-aiice'  No.  1  of  the  S>1andai"d  Oil  romj^any.  located 
approximately  2  miles  n-^'i'thwest  of  'Bolsa  (.'hica"  No.  1,  and  appar- 
ently alont;  the  continnation  of  the  line  of  struetnre,  has  been  drilled 
to  a  depth  of  -K)(>0  feet  witlionl  aii.\  indications  of  petroleum.'  Drillinii' 
alonir  Jhe  northeast  flank  of  the  sii|)pos('(l  fold  indic;ites  that  ]>rodnction 
may  l)e  obtained  as  far  as  a  distance  of  three-fourths  of  a  mile  east  of 
the  axis  as  located  above,  but  not  at  a  distance  of  a  iiiilc  Kou^hly, 
then,  the  area  in  which  productioji  may  be  expected  (based  on  the  data 
available  to  date)  consists  of  a  sti'ip  lyiuir  approximately  tliree-fourths 
of  a  mile  on  either  side  of  a  line  di-awn  between  'Bolsa  Chiea'  No.  1 
and  Pantajjes  Oil  Company  well  .\o.  1.  The  formations  encountered 
on  wel's  drilled  close  to  the  axis  are  as  follows:  From  0  to  500  feet, 
soft,  loose  sands  and  gravels,  pr(»l)td)Iy  belonging  to  the  San  Pedro 
formation  ( Ouaternarx)  ;  fi'om  .")()()  to  700  feet,  conglomerate  and 
boulders  are  found — this  marks  the  top  of  the  Fernando.  Then  fol- 
lows about  KiOO  feet  of  shales  and  sands  of  the  Fernando,  in  which 
there  are  several  tar  sands.  At  about  2250  feet  the  first  ])roductive 
oil  sands  are  encountered.  Wells  drilled  down  the  dip  encounter  the 
fir.st  oil  at  depths  from  2(500  to  .'UOO  feet.  To  date  the  oil  sands  have 
been  penetrated  to  depths  varying  fi-oin  300  to  600  feet.  Wells  drilled 
on  the  northeastern  Hank  have  all  claimed  to  have  encountered  the  same 
productive  sand,  namely,  the  so-called  'Bolsa  sand.'  Whether  this  is 
so  remains  to  lie  proved.  However,  the  general  uniformity  of  dip 
obtained  by  correlating  the  first  productive  sand  encountered  in  these 
wells  would  lead  to  the  belief  that  the  same  sands  have  been  encountered 
in  these  various  wells.  In  the  vicinity  of  the  Huntington  Central  and 
I'antages  wells,  which  are  located  approximately  on  the  axis,  it  is 
probable  that  an  upper  productive  sand  has  been  found  which  does  not 
exist  -^own  the  dip. 

date  of  this  report  twelve  wells  are  ])roducing  and  the  total 
t.c.uv  iu-oduction  is  800(3  barrels,  or  a  dailv  vield  of  G()G  barrels  per 
welf. 

Signal    Hill   District. 

As  stated  above,  the  anticlinal  sli-uctui-e  of  the  Huntington  Beach 
Held  plunges  sharply  to  the  noil  Invest,  beyond  'Bolsa  (Jhica'  well 
Xo.  1.  The  general  line  of  uplift,  however,  nuiy  be  followed  to  the 
northwest,  it  being  marked  by  the  low  hills  just  east  of  Seal  Beach, 
known  as  Landing  Hill,  and  by  other  low  rolling  hills  on  the  north 
-•ide  of  .Alaniitos  Bay.  From  this  point  the  structure  apparently  begins 
to  emerge  again  till  at  Signal  Hill,  northeast  of  Long  Beach,  a  well 
defined  dome  is  apparent  on  the  surface.  The  center  of  the  dome  is 
marked  by  the  circular  hill  known  as  Los  Cerritos,  or  Signal  Hill. 
The  formations  exposed  are  gravels,   sands  and  clays  of  the  upper 

'Since  the  date  of  this  report  a  fair  glrowing  of  oil  has  been  encountered  in  this 
well  below  4000  feet. 


138  CALIFORNIA    STATE    MINING   BUREAU. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  139 

l)eacli  in  a  southeast  diroction,  so  that  it  ])asses  through  well  No.  1  of 
the  llinitin<it()ii  Ccnfral  Oil  Coinpany  and  well  Xo.  1  of  the  TTnrst  Oil 
CompanN-.  and  slii;litly  east  of  well  Xo.  1  of  the  Panta|?es  Oil  Company. 
From  this  point  sontheast  its  location  is  not  known.  Northwest  of 
Bolsa  ('Idea  No.  1  the  struetnre  apparently  plunges  sharply  to  the 
noi'thwi'st.  'Torranee'  Xo.  1  of  the  Standard  Oil  Company,  located 
approximately  2  miles  northwest  of  '  Holsa  Cliica'  Xo.  1,  and  appar- 
ently along  the  continuation  of  the  line  of  structure,  has  been  drilled 
to  a  depth  of  4000  feet  without  any  indications  of  petroleum.*  Drilling 
along  ^he  northeast  Hank  of  the  sui)posed  fold  indicates  that  production 
may  be  obtained  as  far  as  a  distance  of  three-fourths  of  a  mile  east  of 
the  axi.s  as  located  above,  but  not  at  a  distance  of  a  mile.  Roughly, 
then,  tiie  area  in  which  production  may  be  expected  (based  on  the  data 
available  to  ilnto)  consists  of  a  strip  lying  approximately  three-fourths 
of  a  mile  on  either  side  of  a  line  drawn  In'tween  'liolsa  Chica'  Xo.  ] 
and  Pantages  Oil  Company  well  Xo.  1.  The  formations  encountered 
on  wel's  drilled  clo.se  to  the  axis  are  as  follows:  From  0  to  oOO  feet, 
soft,  loose  sands  and  gravels,  probably  belonging  to  the  San  Pedro 
formation  ( Uuatcrnarx  )  ;  from  oOO  to  700  feet,  conglonu'rate  and 
boulders  are  found — this  marks  the  top  of  the  Fernando.  Then  fol- 
lows about  1()00  feet  of  shales  and  sands  of  the  Fernando,  in  which 
th(M-e  are  .several  tar  sands.  A\  about  22r)0  feet  the  first  j)roductive 
oil  sands  are  encountered.  Wells  drilled  down  the  dip  encounter  the 
first  oil  at  depths  from  2()00  to  3400  feet.  To  date  the  oil  sands  have 
been  penetrated  to  depths  varying  from  300  to  600  feet.  Wells  drilled 
on  the  northeastern  Hank  have  all  claimed  to  have  encountered  the  same 
productive  sand,  namely,  the  so-called  'Bolsa  sand.'  Whether  this  is 
so  remains  to  be  proved.  However,  the  general  uniformity  of  dip 
obtained  by  correlating  the  first  productive  sand  encountered  in  these 
wells  would  lead  to  tiie  belief  that  the  same  sands  have  been  encountered 
in  these  various  wells.  In  the  vicinity  of  the  Huntington  Central  and 
Pantages  wells,  which  are  located  approximately  on  the  axis,  it  is 
pi-obable  that  an  upper  productive  sand  has  been  found  which  does  not 
exist   lown  the  di|>. 

date  of  this  rei)ort  twelve  wells  are  producing  and  the  total 
...iii\  jiu-oduction  is  8000  barrels,  or  a  daily  yield  of  6(36  barrels  per 
well". 

Signal    Hill   District. 

As  stated  above,  the  anticlinal  structure  of  the  Huntington  Beach 
Held  plunges  sharply  to  the  northwest,  beyond  'Bolsa  Chiea'  well 
Xo.  1.  The  general  line  of  uplift,  however,  may  be  followed  to  the 
northwest,  it  being  mai-ked  by  the  low  hills  just  east  of  Seal  Beach, 
known  as  Landing  Hill,  and  by  other  low  rolling  hills  on  the  north 
side  of  .Alamitos  Bay.  PVom  this  point  the  structure  apparently  begins 
to  emerge  again  till  at  Signal  Hill,  northeast  of  Long  Beach,  a  well 
defined  dome  is  apparent  on  the  surface.  The  center  of  the  dome  is 
marked  by  the  circular  hill  known  as  Los  Cerritos,  or  Signal  Hill. 
The  formations  exposed  are  gravels,  sands  and  clays  of  the  upper 

'Since  the  date  of  this  report  a  fair  showing  of  oil  has  been  encountered  in  this 
well  below  4000  feet. 


140  CALIFORNIA    STATE    MINING   BUREAU. 

Fernando.  The  dip  on  the  flanks  vary  from  10°  to  25°,  while  the 
phinge  to  the  nortliwest  and  soutlieast  is  about  15°.  The  general 
geological  conditions  here  are  extremely  favorable  for  a  highly  pro- 
ductive field.  At  the  date  of  this  report  three  wells  are  drilling  here. 
The  Shell  Company's  well  cemented  off  water  at  2745  feet,  and  on 
drilling  out  the  cement  encountered  fair  showing  of  oil.  On  a>;count 
of  the  sharp  dips  the  productive  area  will  probably  be  limited  to  a  circle 
of  about  a  half  mile  in  diameter  arouml  the  center  of  the  hill. 

Region    from    Signal    Hill    North    to   the    Inglewood    Hills. 

• 

NorthAvest  from  Signal  Hill  the  structure  again  plunges  sharply  to 
the  northwest,  and  the  Fernando  beds  are  overlaid  by  Quaternary 
sands.  The  general  line  of  uplift,  however,  may  be  followed  from 
Signal  Hill  northwest  to  Dominguez  Hill,  thence  to  Rosecrans,  and 
thence  through  Athens  on  the  Hill,  and  from  there  it  continues  north- 
west, passing  about  a  mile  east  of  Inglewood  and  running  along  the 
highest  ridge  of  the  Inglewood  Hills.  Along  this  entire  distance  it  is 
marked  by  low  rolling  .hills,  and  the  position  of  the  axis  may  be 
barely  determined  by  low  dips  of  2°  and  3°.  In  the  Inglewood  Hills, 
however,  the  position  of  the  axis  is  well  marked  and  dips  of  5°  to  10° 
may  be  obtained.  The  fonnations  exposed  are  loose  sands  and  clays 
of  Quaternary  age.  This  region  has  been  tested  by  approximately 
nine  wells:  The  Union  Oil  Company,  the  Standard  Oil  Company, 
and  the  Highland  Development  Compam^  each  drilling  a  well  at 
Dominguez.  At  Rosecrans,  the  Eddystone  Oil  Corporation  drilled  the 
two  ]\IacKey  wells.  At  Athens  on  the  Hill,  the  Union  Oil  Company 
drilled  the  'Anderson  well,'  and  in  the  Inglewood  Hills  the  Standard 
Oil  Company  drilled  two  wells,  and  the  Bartolo  Oil  Company  drilled 
one  well.  These  were  all  deep  holes,  those  of  the  Standard  Oil  Com- 
pany being  over  5000  feet,  and  in  none  of  them  were  any  favorable 
indications  found.  It  is  probable  that  the  plunge  of  the  structure 
has  buried  the  possible  oil  sands  which  should  occur  at  the  base  of 
the  Fernando  formation  beneath  an  excessive  thickness  of  upper 
Fernando  and  Quaternary  sands  and  clays,  so  that  they  are  beyond 
the  reach  of  the  drill  in  this  area. 

Region    from    the    Inglewood    Hills   to    Beverly. 

From  the  Inglewood  Hills  the  general  line  of  uplift  continues  north- 
west, passing  just  east  of  Culver  City.  From  this  point  on  the  struc- 
ture gradually  emerges  so  that  at  a  point  about  a  mile  west  of  Beverly 
the  oil  sands  are  again  near  enough  the  surface  to  be  within  reach 
of  the  drill.  Tliis  area  is  known  as  the  Beverly  Hills  field.  The  wells 
are  grouped  about  the  axis  of  the  anticline  which  has  a  northwest- 
southeast  trend,  and  run  approximately  along  the  west  line  of  the 
Amalgamated  Oil  Company's  'Rodeo'  lease.  The  total  proven  area 
of  this  field  is  110  acres.  The  total  average  daily  production  in  Decem- 
ber, 1920,  was  450  barrels  of  oil.  The  average  number  of  wells  produc- 
ing was  15,  with  an  average  daily  .yield,  per  well,  of  30  barrels  of  oil 
and  25  of  water. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  141 

Region  of  the  San   Pedro   Hills. 

Tills  n'i>;ion  consists  of  tlio  lulls  that  lie  west  and  northwest  of  San 
Pedro.  The  formations  exposed  here  consist  of  diatomaeeous  shale 
and  sandstone  beds  of  the  Puente  formation  (Monterey  Series).  Along 
the  eastern  and  northern  edijes  the  Puente  is  ovtM-laid  by  a  small  area 
of  loose  sands  and  gravels  belonging  to  the  San  Pedro  formation 
(Quaternary).  The  structure  consists  of  a  main  anticlinal  fold,  with 
a  northwest-southeast  trend,  the  axis  of  which  runs  just  east  of  the 
high  center  ridge  of  the  hills  and  finally  plunges  to  the  south  out  to  the 
sea  at  Point  Fermiu.  Along  this  axis  are  several  seeps  of  heavy  tar, 
and  at  Point  Fermiu,  where  the  plunge  of  the  fold  has  caused  the 
lower  Puente  shale  to  be  overlayed  by  the  upper  sandstone  beds,  seep- 
ages of  heavy  oil  are  found  at  the  contact.  Shallow  wells  drilled  here 
have  encountered  small  showings  of  tar.  On  both  sides  of  the  main 
anticline  there  are  several  minor  folds.  One  of  these  strikes  out  into 
the  valley  in  a  northeast  direction,  halfway  between  San  Pedro  and 
Redondo.  Two  wells  have  been  drilled  on  this  fold,  located  on  the 
Weston  Ranch.  One,  the  Harbor  Crude  Oil  Company's  w'ell,  was 
drilled  to  al)out  1200  feet  and  encountered  small  showings.  The 
second  well,  drilled  by  the  Traders  Oil  Company,  reached  a  depth  of 
nearly  4000  feet.  To  a  depth  of  1800  feet,  loose  sands  and  gravels  of 
the  San  Pedro  formations  were  encountered,  and  small  showings  of 
heav}'  tar  were  found.  Below  1800  feet  the  well  has  been  drilled  in 
'brown  shale'  (Puente  diatomaeeous  shale)  and  occasional  small 
showings  of  oil  have  been  noted.  These .  two  wells  were  favorably 
located,  and  their  failure  to  obtain  anything  more  than  a  showing 
would  indicate  that  this  region  is  not  favoral)le  for  the  accumulation 
of  any  apprecial)le  amounts  of  petroleum.  This  is  probably  due  to  the 
lack  of  reservoir  beds  above  the  Puente  shale. 

Region    Lying   Between   San    Pedro   and   Santa   Monica. 

This  territory  consists  of  flat  lowlands  with  some  low  sand  hills 
along  the  coast  from  Playa  del  Rey  to  Redondo.  There  are  no  surface 
indications  which  give  any  hint  as  to  the  underlying  formations  or 
structure.  This  region,  however,  in  common  Avith  the  other  flat  areas 
of  the  coastal  plain,  has  the  possibility  of  containing  buried  productive 
anticlines.  It  has  been  thought  that  the  low  sand  hills  may  possibly 
be  a  topographic  expression  of  such  a  structure,  and  at  the  date  of 
this  report  approximately  7  wells  are  drilling  in  the  region  east  of 
El  Seguudo  to  test  this  theory  out.  Two  of  these  wells,  the  Milwaukee 
Fountain  Trust  Company's  well  No.  1  and  the  Standard  Oil  Company's 
well  No.  1  on  Sec.  8,  T.  3  S.,  R.  14  W.,  encountered  considerable  gas 
at  about  1600  feet.  There  is  no  evidence  to  date  to  show  whether  or 
not  this  gas  is  connected  with  any  petroleum  deposit.  No  showings 
of  oil  have  been  found.  The  only  manner  in  which  the  possibilities  of 
this  area  can  be  told  is  by  actual  drilling.  This  entire  region  is  worthy 
of  being  examined  carefully  for  evidences  of  buried  structure. 

In  the  preceding  paragraph  all  the  areas  in  the  coastal  plain  district 
in  which  there  is  the  slightest  indication  of  oil,  or  favorable  structure, 
have  been  described.     There  yet  remains  to  classify  the  areas  in  this 


142  CALIFORNIA    STATE   MINING   BUREAU. 

district  in  which  there  is  no  direct  o:eoh)gical  evidence  available  to  indi- 
cate -whether  or  not  they  contain  possible  productive  fields.  These 
areas  consist  of  the  flat  regions  lying  between  the  three  general  lines 
of  structure  above  described.  In  general,  they  consist  of  the  territory- 
south  and  west  from  Los  Angeles  to  Long  Beach  and  Santa  ^Monica, 
and  southeast  from  Los  Angeles  to  Anaheim  and  Santa  Ana.  The  oil 
possibilities  of  these  areas  may  ])e  summed  up  by  stating  that  they  may 
contain  buried  anticlinal  folds  which  may  be  productive.  There  is  no 
direct  evidence  as  to  where,  or  whether,  these  folds  actually  exist 
but  these  areas  are  worthy  of  being  carefully  examined  for  such  a 
possil)ility  and  have  consequently  been  colored  in  blue  on  Plate  I. 

San   Gabriel   Valley. 

This  region  may  be  considered  as  the  territory  lying  north  of  the 
La  ]\Ierced  and  Puente  hills  and  south  of  the  San  Gabriel  ^Mountains. 
The  Puente  sandstone  and  shale,  and  the  Fernando  sands  and  shales, 
which  outcrop  along  the  north  flank  of  the  Puente  and  La  Merced 
hills,  dip  to  the  north  and  probably  underlay  the  greater  portion  of  the 
San  Gabriel  Valley,  resting  on  the  granite  rocks  of  the  San  Gabriel 
Range,  along  the  northern  edge  of  the  valley.  The  Fernando  is 
principally  confined  to  the  northern  slopes  of  the  Puente  and  La 
]\Ierced  hills,  and  is  found  only  in  patches  in  the  valley  proper.  In 
the  San  Jose  Hills,  which  lie  between  Puente  and  Pomona,  the  diato- 
maceous  shale  of  the  Puente  formations  is  domed  up  in  an  anticline, 
and  along  the  nortliern  edge  the  Puente  is  overlaid  by  a  small  area  of 
Fernando.  At  the  western  end.  just  west  of  Pomona,  outcrops  of 
crystalline  rocks  are  found,  and  similar  outcroi)s  are  found  in  the 
north  end  of  the  Puente  Hills,  just  south  of  Pomona.  On  the  axis 
of  the  anticline,  in  the  San  Jose  Hills,  two  wells  have  been  drilled, 
one  l)y  the  Santa  Fe,  and  one  by  the  Shell  Company,  both  wells  l)eing 
drilled  to  a  depth  of  over  3000  feet  in  the  Puente  and  failing  to  find 
any  favorable  indications.  Along  the  eastern  slope  of  the  Puente 
Hills  in  the  vicinity  of  Chino  it  is  possible  that  small  showings  of  oil 
will  be  encountered  by  wells  drilled  here  (see  Chapter  XII,  San 
Bernardino  County,  for  a  further  description  of  this  region),  and 
similar  results  can  probably  be  obtained  by  wells  drilled  along  the 
north  flank  of  the  Puente  Hills  north  of  the  Whittier.  Brea  Canyon 
and  Olinda  fields,  l)ut  it  is  extremely  doulitful  whether  commercially 
productive  wells  ever  will  be  encountered  in  the  San  Gabriel  Valley, 
or  along  the  northern  and  eastern  flanks  of  the  Puente  Hills.  This  is 
due  to  the  unfavorable  structure  and  the  lack  of  reservoir  beds  above 
the  Puente  shale. 

Eastern   Portion  of  Orange  County. 

This  region  will  be  considered  in  this  report  as  that  portion  of  the 
county  lying  east  of  the  Santa  Ana  River  and  Newport  Bay.  The  oil 
possi])ilities  may  be  summed  up  by  stating  that  tlie  region  is  not  a 
favorable  one  for  the  accuuudation  of  peti-oleum.  The  geology  of  the 
region  is  as  follows:  The  main  portion  of  the  Santa  Ana  ^Mountains 
is  composed  of  ancient  cry.stalline  rocks,  mostly  slates  of  Jurassic  age; 
along  the  western  and  southern  flanks,  rocks  of  Chico  age  are  exposed, 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  143 

which,  in  turn,  arc  overlaid  liy  small  patches  of  Kocciic.  This  condi- 
tion exists  in  the  vicinity  of  the  Oranjrc  County  Tai'k,  where  two  wells 
are  drillin;^,  iu  heds  of  Eocene  age. 

Along  the  east  hank  of  the  Santa  Ana  Kiver,  from  Olive  to  Corona, 
the  MontiM-ey  Series  and  the  Fernando  formation,  are  exposed.  These 
are  foUled  in  an  anticline  which  runs  j)arallel  to  the  river  fi'om 
'Horseshoe  Bend'  to  Olive.  This  fold  has  heen  tested  by  approx- 
imately nine  wells,  and  oidy  small  showings  of  oil  have  been  encoun- 
tered, so  that  it  may  be  considered  as  unproductive. 

In  the  Lagnna  Hills  the  formations  exposed  are  mainly  coar.se  sand- 
stone of  Eocene  age.  These  are  overlaid  along  the  edges  of  the 
hills  by  beds  of  sandstone  and  shale  of  tlic  Monterey  Series.  There  are 
several  minor  anticlines  in  these  hills,  one  of  which  is  located  at  the 
edge  of  the  hills  south  of  Irvine  and  west  of  the  Laguna  road.  The 
II.  K.  and  T.  Company  has  drilled  a  well  on  this  fold  to  a  depth  of 
nearly  3000  feet  without  any  encouraging  results. 

In  the  flat  area  running  from  Tustin  to  El  Toro  the  diatomaceous 
shale  of  the  Montei-ey  is  present,  occupying  a  synclinal  trough  between 
the  Santa  Ana  ^lountains  and  the  Laguna  Hills.  This  condition  con- 
tinues .southeast  through  the  Capistrano  district  to  the  San  Uiego 
County  line.  Section  AB,  Fig.  10,  shows  this  general  structure,  and 
the  formations  exposed.  Following  is  a  l)rief  description  of  these 
formations:  The  Cretaceous  consists  of  al)out  ^oOO  feet  of  conglomerate 
sandstone  and  shale.  The  Eocene  consists  of  the  following  beds :  At  the 
base  about  1000  feet  of  shale  characterized  by  dark  red  aiul  |^uri)le 
clay  beds,  comi)rised  of  fine  fragments  derived  from  sei'pentine  rocks, 
and  similar  to  the  'Red  Beds'  of  the  Coalinga  lield.  Above  this  is 
found  about  2000  feet  of  coarse  white  sandstone,  and  finally  at  the 
toj)  of  these  is  another  sei'ies  of  shales  about  1000  feet  in  tliiclvness. 
The  base  of  the  Miocene  is  characterized  by  an  extremely  coarse  con- 
glomerate, made  up  of  fragments  of  schist,  and  of  a  thickness  of  over 
200  feet.  Above  this  conglomerate  is  found  about  oOO  feet  of  Vaqueros 
sandstone  and  IKK)  feet  of  JMonterey  shale,  which  occupy  the  trough 
of  this  .syncline.  Just  north  of  Capistrano  there  is  a  minor  fold  in  the 
^Monterey  on  which  the  Cnion  Oil  Comi)any  has  drilled  a  well  to  a 
depth  of  4000  feet  without  any  indications  of  petroleuuL 

The  .statement  made  at  the  beginning  of  this  section  that  the  region 
is  not  favorable  for  the  accumulation  of  oil  is  based  on  the  following 
facts:  The  greater  portion  of  this  area  is  covei't'd  l)y  rocks  that  are 
older  than  the  oil-bearing  formations  of  Southern  California,  and  which 
show  no  oil  nor  contain  any  beds  that  are  capable  of  forming  oil. 
The  Monterey,  which  contains  oil  in  other  regions  in  Southern  Cali- 
fornia, is  found  in  this  region  only  in  a  small  thickness,  and  in  an 
unfavorable  structure,  without  reservoir  beds  for  the  oil  to  collect  in. 
Lastly,  to  the  best  of  the  writer's  knowledge,  there  are  no  surface 
indications  of  petroleum,  such  as  seepages  or  gas  blows,  in  the  region 
lying  east  of  Tustin. 


144 


CALIFORNIA    STATE    MINING   BUREAU. 


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PETROLEUM    RESOURCES    OF    CALIFORNIA.  145 

CHAPTER  XL 
Sax  Diego  and  Imperial  Counties. 

San    Diego    County. 

Topogi-apliically  and  ijeolofrii-'ally,  San  Diego  may  be  divided  into  two 
areas,  one  a  mountain  higliland  area  covering  approximately  eleven- 
thirteenths  of  the  county  and  the  other  a  narrow  belt  of  about  fifteen  miles 
ill  widtli  along  the  coast,  cliaracterized  b}'  broad,  flat-topped  sea 
terraces. 

Tiie  highland  area  is  a  i)art  of  a  great  fault  block,  which  is  character- 
ized by  a  steep  descent  to  the  Imperial  County  side  and  a  gradual  slope 
on  the  west  to  the  terraces  of  the  coastal  plain.  The  formations  of  the 
highland  region  consist,  for  the  most  part,  of  granitic  rocks,  together 
witii  smaller  areas  of  lavas  and  ancient  crystalline  schists  and  lime- 
stones. As  none  of  these  are  capable  of  containing  oil,  no  further  discus- 
sion will  be  given  of  the  highland  area.^ 

The  coastal  strip  is  made  up  of  sedimentary  rocks,  ranging  in  age  from 
the  Chico  (upper  Cretaceous)  to  the  recent  beach  terraces.  This  area 
may  best  be  discussed  by  dividing  it  into  two  parts,  consisting  of  the 
region  north  of  Del  ^lar  and  the  region  between  Del  Mar  and  the  Mexican 
boundary. 

In  the  region  north  of  Del  j\Iar,  the  sedimentaries  are  lying  against  the 
crystalline  rocks,  in  a  gentle  monocline  dipping  about  10°  to  the  west. 
The  following  formations  are  exposed :  Eocene,  lower  Miocene  and  recent 
terrace  deposits.  The  Eocene  is  best  exposed  along  Santa  IMargarita 
Creek,  between  Ysidora  and  the  Home  Ranch.  It  consists  of  about  2500 
feet  of  medium  coarse  white  sandstone  and  above  the  sand  is  about  2000 
feet  of  fine,  tan-colored,  muddy  shales.  North  of  Santa  ^Margarita  Creek 
the  base  of  the  Eocene  is  charac^terized  by  red  and  purple  clay  beds, 
known  as  the  Red  Beds  and  referred  to  in  the  description  of  the  Eocene 
in  the  vicinity  of  Capistrano  (Orange  County).  On  account  of  the 
strike  of  the  beds,  which  is  approximately  north  and  south,  the  upper 
shales  disappear  and  run  out  to  sea  just  south  of  Oceanside  and  from 
this  point  on  south  only  the  lower  white  sandstone  beds  are  exposed,  at 
times  covered  along  the  terraces  by  recent  deposits.  The  entire  Eocene 
Series  is  continuous  north  i-nto  Orange  County  and  connected  with  for- 
mations of  the  same  character  and  age,  described  in  the  vicinity  of  Capis- 
trano. In  the  region  at  the  head  of  San  Mateo  Creek,  it  is  possible  that 
the  Eocene  is  underlaid  by  shales  and  conglomerates  of  Chico  age,  which 
in  turn  rest  on  the  granite.  The  lower  Miocene  consists  first  of  about 
500  feet  of  coarse  conglomerate  made  up  of  flat  fragments  of  crystalline 
schist,  prol)ably  derived  from  rocks  of  the  Franciscan  formation.  This 
conglomerate  is  a  continuation  of  the  conglomerate  beds  referred  to  in 
the  descriptions  of  the  eastern  portion  of  Orange  County.  It  is  most 
prominent  in  the  vicinity  of  San  Onofre  jNIountain,  and  disappears  in 
its  southward  extension  ])y  striking  out  to  sea  at  Oceanside. 

'Certain  areas  of  Tertiary  sedimentary  rocks  found  along  the  eastern  border  of  the 
county,  near  Carrizo  Creek  and  San  Felipe  Creek,  will  be  discussed  in  connection 
with  Imperial  County. 

10—13322 


146  CALIFORNIA    STATE   MINING   BUREAU. 

The  Vaqueros  sandstone  and  senii-diatoniaceous  shale  of  the  Monterey 
whicli  overlies  the  conglomerate  farther  north  in  Orange  County  do  not 
outcrop  in  San  Diego  County,  but  they  are  probably  present  beneath  the 
sea  terraces  from  the  county  line  as  far  south  as  Santa  ^largarita  Creek. 
In  Fig.  11,  Sec.  AB  shows  the  general  structure  and  character  of  the 
formations  north  of  Santa  Margarita  Creek.  Between  Oceanside  and 
Del  Mar,  the  only  sedimentary  formation  present  is  the  white  sandstone 
member  of  the  Eocene,  dipping  at  a  low  angle  to  the  west.  There  is  no 
evidence  of  petroleum  anywhere  in  the  area  between  the  Orange  County 
line  and  Del  ^lar.     The  following  wells  have  been  drilled  here : 

Clark  Oil  Company  well  east  of  La  Costa,  NW.  J  of  Sec.  26,  T.  12  S., 
E.  4  W.,  depth  2665,  now  1)eing  redrilled  by  the  La  Costa  Oil  Company. 
Pacific-Laguna  Company  well  east  of  La  Costa,  SW.  ]  of  Sec.  26,  T.  12  S., 
R.  4  ^Y.,  depth  1400  feet.  Both  wells  failed  to  show  oil.  At  the  present 
time  the  Oceanside  Oil  and  Gas  Company  is  drilling  a  well  in  the  Eocene 
shales  about  a  mile  and  a  half  nortlieast  of  the  town  of  Oceanside,  and 
has  reached  a  depth  of  about  1600  feet. 

The  La  Costa  Oil  Company  has  taken  over  the  old  Clark  well,  which 
was  abandoned  some  years  ago,  and  redrilled  to  a  depth  of  2700  feet. 
Showings  of  oil  and  gas  have  been  reported. 

In  the  area  between  Del  iNIar  and  the  IMexican  boundary  the  general 
structure  partakes  of  the  nature  of  a  very  flat  syncline,  the  axis  of  which 
parallels  the  coast  about  five  miles  inland.  Beds  of  the  following  ages 
are  found  outcropping:  Cretaceous,  Eocene  and  Pliocene. 

The  Cretaceous  is  represented  by  the  Chico  and  consists  of  beds  of 
medium  grained  sandstone,  blue-gray  in  color  and  interbedded  by  thin 
layers  of  dark  colored  shales.  It  outcrops  on  the  surface  only  at  the 
southern  end  of  Point  Loma  and  in  the  sea  cliff  at  La  JoUa.  It  pro])ably 
underlies  the  entire  area.  The  total  thickness  is  not  known,  but  well 
logs  indicate  that  it  is  over  3000  feet. 

The  Eocene  is  probably  represented  by  beds  of  IMeganos  age,  and 
consists  of  clay  shales  and  white  sandstone,  with  a  total  thicknes.s  of 
about  1000  feet.  The  outcrops  are  limited  to  Point  Loma,  the  sea  cliffs 
from  La  JoUa  to  Del  ^lar,  the  vicinity  of  Soledad  Mountain  and  at  low 
levels  in  Soledad  and  Rose  canyons.  The  Pliocene,  known  locally  as 
the  San  Diego  formation,  overlies  almost  the  entire  area.  It  consists 
of  beds  of  sandstone  conglomerate  and  clay  shales,  with  a  total  thickness 
of  about  500  feet. 

In  Fig.  11,  Sec.  CD  shows  the  probable  structure  in  the  vicinity  of 
La  JoUa  and  San  Diego.  The  following  wells  have  been  drilled  in  this 
area  :^ 

La  Tengo  Oil  Companv.  Well  one  mile  north  of  Tia  Juana,  in  SW.  i 
Sec.  31,  T.  18  S.,  R.  1  W.,  depth  3290  feet,  reported  oil  and  gas ;  drilled 
in  1911. 

Tia  Juana  Valley  Oil  Company.  Well  about  two  and  one-half  miles 
south  of  Nestor  and  a  few  hundred  vard.s  north  of  the  ^Mexican  border, 
See.  9,  T.  19  S.,  R.  2  W.,  known  as  the  Scott  well.  Depth  1474  feet ; 
drilled  in  1910.  The  Community  Oil  Company  has  recently  made  an 
attempt  to  clean  this  Avell  out. 

^See  Fourteenth  Report  of  the  State  Mineralogist,  pp.  70S-712. 


PETROLEUM   RESOURCES   OP   CAIJPORNIA. 


147 


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148  CALIFORNIA    STATE    MINING   BUREAU. 

Otay  Oil  Coiiipaiiy.  Si)iitlieast  of  Otay,  NE.  ]  of  Sw.  30,  T.  IS  S., 
R.  1  W.  Dc'i)tli  2185  fcH't;  clrillcil  in  IDIO.  Reported  showing  of  oil 
and  gas. 

Bal])oa  Oil  Comi)any.  Well  in  tlie  :\lission  Valley.  Piiehlo  Lot  1105. 
Depth  5t)75  feet;  drilled  1911. 

San  Elijo  Oil  Company.  Two  wells  just  west  of  Sorrento  Station; 
Pueblo  Lot  27.     Depths  1599  feet  and  1303  feet. 

The  Pnterbaugh  well  at  ^loreno.  about  one  and  one-half  miles  north 
of  Mission  Valley.     Depth  1200  feet. 

The  Chula  Vista  well,  drilled  near  the  town  of  Chula  Vista,  reached 
a  depth  of  1812  feet. 

At  the  present  time  the  followino;  wells  are  drillinp-: 

Linda  Vista  Petroleum,  See.  23,  T.  15  S.,  R.  3  W. 

Community  Oil  Company  has  started  the  following  wells:  "Well  No.  1 
(old  Scott  well),  Sec.  9,  T.  19  S.,  R.  2  W.  The  company  is  endeavoring 
to  clean  this  well  out.  Well  No.  2,  Sec.  4,  T.  19  S.,  R.  2  W.  AVell  No.  3, 
T.  17  S.,  R.  2  AV.,  Lot  17.  AVell  No.  5,  one  mile  east  of  Moreno,  T  15  S., 
R.  3  W. 

The  Tecalote  Dome  Oil  Company.  T.  16  S.,  R.  3  W.,  Pueblo  Lot  1272. 
Depth,  2650  feet. 

Mission  Valley  Company,  Sec.  24,  T.  16  S.,  R.  3  W.,  Pueblo  Lot  1108. 

While  most  of  the  wells  which  have  been  drilled  or  are  drilling  at  the 
present  time  report  showings  of  oil  or  gas,  the  significant  fact  is  that  no 
actual  production  of  oil  ha.s  ever  been  obtained. 

The  possibilities  of  obtaining  oil  in  this  area  are  not  very  favorable. 
There  is  apparently  a  total  lack  of  any  actual  evidence  of  petroleum, 
such  as  seepages  or  gas  blows.  The  formations  exposed  show  neither 
favorable  structure  nor  contain  sufficient  organic  material  to  form  anv 
noticeable  quantities  of  petroleum.  TTnless  evidence  is  found  to  disprove 
these  facts,  further  drilling  in  this  area  is  a  waste  of  money. 

Following  is  a  portion  of  a  report  on  the  oil  possibilities  of  San  Diego 
County,  from  a  press  bulletin  of  the  United  States  Geological  Survey, 
]\Iareh,  1920,  based  on  an  examination  made  by  Mr.  W.  S.  W.  Kew : 

"The  region  was  recently  examined  by  William  S.  W.  Kew.  of  the  United  States 
Geological  Survey,  Department  of  the  Interior,  who  is  of  opinion  that  San  Ui(>go  County 
is  not  a  favorable  place  in  which  to  drill  test  wells  for  oil.  Tlie  reasons  for  this  opinion 
can  be  summarized  as  follows:  (1)  The  principal  formations  that  furnish  oil  elsewhere 
in  California  are  not  found  in  San  Diego  County.  (2)  The  Upper  Cretaceous  strata, 
which  probably  constitute  a  large  part  of  the  sedimentary  beds  at  San  Diego,  are  not 
commercially  productive  in  other  parts  of  California,  and  there  is  nothing  to  indicate 
that  they  will  be  productive  in  the  southern  part  of  tlie  state.  (3)  The  Eocene  strata, 
though  of  the  same  age  as  the  oil-bearing  strata  in  other  parts  of  California,  do  not 
appear  to  contain  oil  liere.  As  far  as  known,  no  structural  features  that  are  favorable 
to  the  aucumulation  of  oil,  such  as  anticlines,  have  been  discovered  in  San  Diego  County. 
As  the  strata  dip  very  gently  and  at  many  places  lie  nearly  flat,  careful  geologic  work 
would  be  necessary  to  locate  these  structural  features.  If  drilling  is  continued  near 
San  Diego,  the  structure  should  be  carefully  studied  in  order  to  determine  the  most 
advantageous  places  for  sinking  wells  to  test  the  oil  sands  that  are  reported  to  have 
been  penetrated  in  previous  tests.." 

Imperial    County. 

Imperial  County  occupies  the  desert  region  in  the  extreme  southea.stern 
portion  of  the  state.  Its  length  east  and  west  is  approximately  100  miles 
and  its  width  north  and  south  is  about  55  miles.  About  one-half  the 
county  is  a  great  flat  plain,  know'ii  as  the  Imperial  Valley,  the  major 
portion  of  which  is  below  sea  level.  This  great,  flat  valley  represents 
the  old  sea  bed  of  the  mo.st  northerly  extension  of  the  Gulf  of  California, 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  149 

and  has  been  separatod  from  tho  pi-esent  gulf  by  a  barrun-  of  sediiiionts 
built  up  by  the  (\)b)rado  Kiver.  The  waters  of  the  gulf  in  this  isolated 
l)ortioii  gradually  evaporated,  leaving  the  l)asiu  of  Saltou  Sink.  In 
1904,  the  Colorado  River  broke  through  its  western  l)ank  and  partly 
retilled  Salton  Sea.  A  little  water  is  still  running  into  it  by  way  of 
the  New  River.  At  the  ])resent  time  the  total  area  oeeupied  by  the  sea 
Is  about  -70  s<|uare  miles,  of  whieh  280  square  miles  lie  within  the 
county,  oceupying  the  northeast  corner.  The  surface  of  the  water  is 
about  250  feet  below  sea  level  and  the  depth  is  about  37  feet. 

On  two  sides  the  Imperial  Valley  is  surrounded  by  mountain  ranges. 
On  the  west  the  highland  area  of  western  San  Diego  County  (Peninsula 
Range)  rises  abruptly  from  the  valley  tloor  along  a  line  marked  approxi- 
matelv  bv  the  boundarv  between  the  two  counties.  Superstition  ^Nloun- 
tain  is  a  detached  range  lying  out  in  the  valley  northwest  of  the  town 
of  Imperial. 

On  the  east,  forming  the  northeastern  one-half  of  the  county,  are  sev- 
eral mountain  ranges,  chief  of  which  are  the  Chocolate  ^Mountains.  This 
portion  of  the  county  may  be  considered  as  having  no  oil  possibilities. 
The  fornuitions  which  are  exposed  consist  mainly  of  ancient  nietaniorphic 
rocks,  probably  of  pre-Caml3rian  age.  In  various  localities  these  meta- 
morphics  are  covered  by  lava  tiows  of  a  much  younger  period.  Along  the 
west  slope  of  the  Chocolate  ^Mountains  are  outcrops  of  vivid  colored 
sands,  clays  and  gravels,  i)robably  of  Pliocene  age.  The  character  of 
the  formations  and  the  total  lack  of  any  evidence  of  petroleum  make 
this  region  unfavorable. 

That  portion  of  the  county  which  is  underlaid  mainly  by  Tertiary 
sedimentary  rocks,  and  C(uitains  the  only  areas  worth  investigating,  lies 
west  of  the  main  line  of  the  Southern  Pacific  Railroad,  and  consists  of 
approximately  a  little  more  than  one-half  the  county  (Plate  No.  VI 
shows  this  area).  AVith  the  exception  of  a  strip  about  ten  miles  wide 
along  tliQ.  western  border,  and  the  areas  around  Superstition  Mountain 
and  Yuba  Buttes,  this  district  is  covered  entirely  by  recent  deposits  of 
fine  silt  and  sand.  The  geology  of  it  will  therefore  have  to  be  determined 
by  studying  the  formations  exposed  in  the  localities  mentioned  above. 
The  strip  along  the  western  border,  which  contains  the  exposures  of  tlie 
underlying  formatioiLS,  is  formed  by  spurs  of  the  Peninsula  Range  jutting 
out  into  the  valley.  The  principal  spurs  are  Coyote  IMountain  and  Fish 
Creek  IMountain.  North  of  San  Felipe  Creek  there  is  a  series  of  low, 
rolling  hills,  which  nuiy  be  considered  as  the  southeastward  extension 
of  the  Santa  Rosa  ^lountain,  and  which  contain  excellent  exposures  cf 
the  sedimentary  formations.  Superstition  Mountain,  l.ying  mainly  in 
Townships  18  and  14  S.  and  Range  11  E.,  has  a  core  of  crystalline  rocks 
and  the  Tertiary  sedimentaries  are  exposed  in  the  low,  rolling  hills  to 
the  northeast.  Yuha  Buttes  consists  of  a  few  low  mounds  in  Sees.  28  and 
33,  T.  16  S.,  R.  11  E.,  which  are  formed  by  an  uplift  in  sedimentary 
strata. 

The  oldest  rocks  in  this  district  consist  mainly  of  marbles  and  schists, 
into  which  have  been  intruded  masses  of  granitic  rocks  and  pegmatite 
dikes.  The  age  of  this  complex  crystalline  series  is  not  deHnitcly  known, 
but  Fairbanks^  believes  it  to  be  of  Carboniferous  age.     It  is  a  part  of 

'Eleventh  Annual  Report  of  the  State  Mineralogist,  11.  W.  Fairbanks,  p.  90,  1893. 


150  CALIFORNIA    STATE   MINING   BUREAU. 

the  crystalline  series  that  form  the  highland  area  of  San  Diego  County, 
and  is  coninionly  referred  to  as  the  basement  complex.  AVithin  this 
area  it  is  found  outcropping  along  the  north  slope  of  Fish  Creek  Moan- 
tain,  along  the  central  core  of  Coj^ote  and  Superstition  mountains,  and 
finally  in  the  group  of  mountains  between  Coyote  Wells  and  the  Mexican 
border. 

The  next  oldest  formation  is  a  highly  colored  Andesitic  lava  flow, 
approximately  200  feet  in  thickness.  It  lies  unconformable  upon  the 
eroded  surface  of  the  basal  complex  and  is  best  exposed  running  east  and 
west  along  the  central  ridge  of  Fish  Creek  Mountain  and  in  small  patches 
on  the  eastern  slope  of  Coyote  IMountain.  The  age  i>s  probably  middle 
Tertiary. 

Ljdng  with  marked  unconformity  upon  the  lava  and  basement  com- 
plex is  a  series  of  sedimentary  rocks,  first  described  by  Kew^  and  called 
by  him  the  Carrizo  formation.  The  basal  beds  of  this  formation  consist 
of  medium-coarse  gray  sandstone,  together  with  beds  of  coarse  conglom- 
erate. The  sandstone  is  characterized  by  numerous  fossils  and  coral 
reefs.  Above  this  sandstone  member  are  found  beds  of  fine  sandy  shales, 
silts  and  clay  shales.  The  fine  clay  shales  are  usually  of  a  chocolate 
color  and  bear  at  first  sight  a  resemblance  to  certain  varieties  of  diato- 
maceous  shale.  However,  an  examination  under  the  microscope  shows 
no  diatoms  and  the  beds  apparently  are  lacking  in  any  appreciable 
amount  of  organic  matter.  The  upper  shale  beds  are  characterized  by 
fossil  reefs  made  up  of  the  remains  of  oysters  and  pectens.  The  age  of 
the  Carrizo  formation  is  probably  upper  Miocene  to  lower  Pliocene,  and 
the  thickness  between  3000  and  4000  feet. 

The  formation  is  exposed  in  the  following  places:  at  Yuha  Buttes,  at 
Coyote  Mountain,  along  the  south  slope  of  Fish  Creek  Mountain,  in  the 
low  hills  north  and  east  of  Superstition  Mountain,  in  the  low  hills  north 
of  San  Felipe  Creek,  and  continuing  north  to  the  Riverside  l)oundary. 
This  latter  area  also  continues  westward  into  San  Diego  County  as  far 
as  Clark  Lake. 

Considerable  movement  has  taken  place  in  the  valley,  and  the  Carrizo 
beds  have  been  sharply  folded  into  numerous  structures.  The  principal 
areas  are  as  follows:  Yuha  Buttes  is  a  domed  anticline.  A  plunging 
anticline  apparently  strikes  out  of  the  east  slope  of  Coyote  ]\Iountain. 
There  are  numerous  folds  to  the  east  and  north  of  Superstition  Moun- 
tain. Carrizo  Creek  marks  the  axis  of  a  syncline  running  east  and  west. 
In  the  area  north  of  San  Felipe  Creek,  the  major  fold  runs  southeast 
along  the  south  line  of  T.  11  S.,  Es.  9  and  10  E.,  and  at  least  two  minor 
folds  diverge  from  this  structure  and  strike  to  the  northeast. 

Seepages  of  oil  and  the  presence  of  asphaltum  have  been  frequently 
reported  as  being  found  in  the  Imperial  Valley,  and  the  majority  of 
wells  now  drilling  in  the  valley  have  reported  showings  of  oil  and  gas. 
However,  none  of  these  reputed  seepages  or  showings  of  oil  have  ever 
been  verified  by  any  representatives  of  the  State  IMining  Bureau. 

The  possilnlities  of  finding  oil  in  the  valley  may  be  summed  up  as 
follows :  while  the  structure  of  the  Carrizo  beds  is  extremely  favorable 
for  its  accumulation,   there  is  apparently  no  formation   present  that 

^Univer.sity  of  California.  Riill.  5,  Vol.  S.  191  1.  Tertiary  Echinoids  of  the  Carrizo 
Creek  Region  in  the  Colorado  Desert.     By  W.  S.  W.  Kew. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  151 

could  form  potroloum.  From  tho  above  description  of  the  rocks  exposed, 
it  is  evident  that  tlie  only  beds  that  could  possibly  contain  oil  are  those 
of  the  Carrizo  formation  and  it  is  equally  evident  that  this  formation 
does  not  contain  sufficient  organic  matter  to  form  any  noticeable  amount 
of  petroleum.  It  should  also  be  noted  that  the  Carrizo  beds  are  sharply 
folded  and  tilted,  and  if  any  oil  were  present  it  would  show  as  seepages 
along  the  outcrops.  The  only  possibility  of  finding  oil  lies  in  the  bare 
chance  that  somewhere  in  the  valley  there  are  beds  of  organic  shale,  the 
outcrops  of  which  are  hidden  by  the  overlapping  of  the  Carrizo  beds 
against  the  crystalline  rocks.  If  such  beds  existed,  and  there  is  no 
direct  evidence  that  they  do,  oil  would  tend  to  collect  in  the  anticlinal 
structure  of  the  Carrizo  formation. 

The  wells  now  drilling,  a  list  of  which  is  given  below,  are  nearly  all 
favorably  located  and  should  conclusively  prove  or  disprove  the  presence 
of  oil  in  the  county.  Recent  reports  have  been  made  on  the  county  by 
Mr.  W.  S.  "W.  Kew^  and  I\Ir.  Irving  Augur.- 

Following  is  a  portion  of  Kew  's  report : 

"The  Carrizo  Creek  beds  have  been  foMed  into  numerous  arches  (anticlines)  and 
troughs  (synclines).  One  of  the  larger  anticlines  that  seems  favorable  to  the  accumu- 
lation of  oil  lies  north  of  San  Felipe  Creek.  Others  are  on  the  north,  east  and  south 
sides  of  Superstition  Mountain,  the  core  of  which  is  granite.  The  southeastern  exten- 
sion of  this  mountain  is  an  finticline,  which  extends  from  the  granite  in  the  southeast 
corner  of  T.  14  S..  R.  11  E.,  across  the  southwest  corner  of  T.  14  S.,  R.  12  E.,  into 
T.  1.5  S..  R.  12  E.  The  beds  along  the  anticline  in  this  area  dip  rather  steeply  away 
from  its  axis,  which  plunges  gently  to  the  southeast.  Anticlines  also  occur  north 
and  northeast  of  the   eranite  center  of  Superstition   Mountain. 

"The  strata  in  the  hills  between  San  Felipe  Creek  and  the  Salton  Sea  have  beeen 
considerably  folded,  though  southeast  of  Seventeen  Palms  there  appears  to  be  only 
one  major  anticline  or  dome  upon  wliich  subsidiary  folds  are  superposed.  This  main 
anticline  trends  southeastward  across  the  soxitheastern  part  of  T.  11  S..  R.  9  E.,  and 
the  southwestern  cart  of  T.  11  S.,  R.  10  E..  and  extends  into  T.  12  S.,  R.  10  B.  The 
highest  point  on  this  anticline— tlie  apex  from  which  it  plunges  to  the  northwest  and 
southeast — is  near  the  line  between  Sees.  2.5  and  36.  T.  11  S.,  R.  9  E.,  and  the  angle 
of  plunge  is  about  10°  to  20°,  becoming  less  steep  with  increase  of  distance  from  the 
apex.  The  beds  dip  from  the  axis  of  the  anticline  at  an  average  general  rate  of 
15°  to  30°.  but  tliose  that  form  the  subsidiary  folds  attain  at  some  places  a  dip  as 
high  as  55°. 

"In  general,  the  top  of  the  anticline  is  fairly  flat,  though  it  is  broken  into  minor 
folds.  The  well  of  the  Imperial  Valley  Oil  and  Development  Association  is  on  the 
east  side  of  the  higliest  point  or  apex  and  the  Diamond  Bar  well  is  on  the  west  side; 
both  wells  are  only  a  short  distance  noi-tli  of  the  axis  of  the  anticline.  This  anticline 
is  probably  one  of  the  most  promising  in  Imperial  Valley,  and  the  test  wells  are 
properly  located  to  prove  tlie  presence  or  absence  of  oil  there. 

".Seepages  and  oil  sands  in  Imperial  Valley  have  frequently  been  reported,  but 
none  of  these  reports  have  been  authenticated,  and  samples  of  so-called  oil  sands 
have  always  proved  to  be  sands  blackened  by  manganese  oxide,  but  it  is  reliably 
reported  that  asnhalt  occurs  on  the  southeast  edge  of  a  dry  lake  west  of  Signal 
Mountain.  aViout  3  miles  south  of  the  Mexican  border.  Several  wells  drilled  for  oil 
in  the  valley  have  not  yielded  favorable  results.  In  1902  two  wells  were  sunk 
at  Yuha  Buttes,  in  Sec.  32,  T.  16  S.,  R.  ir  E.,  on  a  domelike  uplift  in  the  Carrizo 
Creek  beds.  One  of  these  wells  was  sunk  1300  feet  without  getting  any  indication 
of  oil  except  a  little  gas.  The  Harper  well,  also  known  as  the  Me.squite  drill  hole, 
in  the  northeast  corner  of  Sec.  34,  T.  12  S.,  R.  10  E.,  is  reported  to  have  gone  700 
feet  and  to  have  struck  a  little  gas.  It  now  yields  water.  The  Hanna  well,  on  the 
north  side  of  Fish  Creek  Mountain,  is  said  to  be  SOO  feet  deep.  The  Hudson  well,  in 
the  southwestern  part  of  T.  14  S..  R.  11  E.,  is  about  500  feet  deep.  The  result  of 
what  is  known  as  the  Barrett  drill  hole,  sunk  near  the  mouth  of  Carrizo  Canyon, 
is  not  known. 

"The  geology  structure  in  Imperial  Valley  is  exceptionally  favorable  to  the  accumu- 
lation of  oil,  and  if  any  of  the  beds  of  the  Carrizo  Creek  formation  contain  oil  it 
should  be  found  in  some  of  the  anticlines  that  are  now  being  tested.  These  beds 
show  no  surface  indications  of  oil,  but  in  some  of  the  wells  they  have  yielded  a  little 
gas.  As  these  beds  crop  out  in  great  thickness,  and  thev  are  faulted  at  many  places, 
they    should    show    seepages,    or    oil-impregnated    sands,    if    they    contain    oil.     The 

JU.  S.  Geological  Survey.  Press  Bull.,  June,  1920.  Oil  Prospects  of  the  Imperial 
^  alley.      By  Mr.  W.  S.  W.  Kcw. 

•.n.iT^"^^''"'''^    State    Mining    Bureau.     Summary    of    Oil    Field    Operations    for    April, 
1920.     Resume  of  all  Well  Operations  in  the  Imperial   Valley.     By  Irving  Augur. 


152  CALIFORNIA    STATE   MINING   BUREAU. 

absence  of  such  seepages  is  the  strongest  evidence  against  the  presence  of  oil  in 
the  Imperial  Valley,  but  it  is  not  conclusive.  In  Mr.  Kew's  opinion,  Imperial  Valley 
should  be  tested  for  oil.  but  the  tests  should  be  made  only  by  persons  or  companies 
who  can   afford  to   invest   large   sums   of   money   with  poor  chances   of  success." 

Following  is  a  list  of  the  welLs  now  drilling  (see  Plate  VI)  : 

In  Sec.  9,  T.  16  S.,  R.  10  E.,  the  San  Diego  and  Imperial  Valley  Oil 
Company  has  a  well  down  to  a  depth  of  al)oiit  1100  feet.  The  hole  known 
as  the  'James  well'  is  loeated  on  the  south  side  of  a  plunging  anticline 
in  the  Carrizo  formation. 

In  Sec.  6,  T.  16  S.,  R.  11  E.,  the  Southwestern  Pipe  Line  and  Petroleum 
Company  has  a  well  down  to  a  depth  of  about  700  feet.  This  well  is 
located  in  the  flat  lands  of  the  valley  and  apparently  no  structure  is 
present.  In  the  area  just  north  of  the  well  the  writer  noted  several  out- 
crops of  coarse  sandstone  dipping  about  40°  to  the  east.  This  exposure, 
however,  was  too  meager  to  determine  whetlier  any  structure  was  actually 
present.  The  log  of  the  well  indicates  that  the  beds  penetrated  belong  to 
the  upper  portion  of  the  Carrizo  formation. 

In  Sec.  11,  T.  16  S..  R.  14  E.,  near  Holtville,  the  104  Oil  and  Drilling 
Companv  has  a  well  dritliiig. 

In  Sec.  32,  T.  11  S..  R.  10  E.,  the  Imperial  Valley  Oil  and  Development 
Company  has  a  well  known  as  the  Brawley  well,  which  is  located  on  a 
dome  in  the  Carrizo  formation.     A  depth  of  2570  feet  has  been  reached. 

In  Sec.  25,  T.  11  S.,  R.  9  E.,  L.  Lechtenberger  is  drilling  a  well  known 
as  the  Diamond  Bar  well,  which  is  located  on  a  dome  in  the  Carrizo  for- 
mation.    A  depth  of  3083  feet  has  been  reached. 


PETROLEUM    RESOURCES    OF    CALIFORNIA.  153 


chapt?:r  XII. 

The  Desert  Region. 

(Includes  the  counties  of  Riverside,  S;in  lU^rnardino,  Nortlieastern  Los  Angeles, 

Eastern  Kern  and   Itno  and   INlono.) 

This  region,  for  the  purpose  of  this  r('i)ort.  will  be  regarded  as  lying 
east  of  the  Sierra  Nevada,  Tehaeliapi  ^lountains,  Sierra  Liebre  Range, 
San  Gabriel  Range,  and  east  of  and  including  the  San  Bernardino 
Mountain.s  and  Peninsula  Range.  This  groui)  of  mountnins,  running 
approximately  north  and  south,  with  a  slight  we.stward  l)end  in  the  Ante- 
lope Valley  region  of  Los  Angeles  County,  effectually  shuts  oft'  the  desert 
area  from  the  southern  coastal  i)lain  and  the  central  valley  of  California. 

As  the  area  will  be  discussed  by  counties,  the  fertile  western  portions 
of  Riv(>rside  and  San  Hernardino  counties,  lying  west  of  the  mountain 
and  properly  lielonging  to  the  coastal  area,  are  discussed  partly  here  and 
partly  in  Chapter  X. 

Imperial  County,  which  is  a  jiortion  of  this  area,  has,  on  acconnt  of 
slightly  dift'erent  geological  formations  and  recent  attempts  at  develop- 
ment, i)een  included  in  a  separate  chapter  (XI)  with  San  Diego  County. 

Wliile  this  region  is  commonly  know-n  as  the  dese-rt  area,  it  is  far  from 
being  a  land  of  broad  desert  plains,  as  possi])ly  one-half  of  the  territory 
is  occupied  by  higli  mount;) in  chains,  which  rise  with  striking  abruptness 
from  the  desert  floor. 

In  Mono  and  Inyo  counties  these  mountain  chains  form  a  series  of 
paraHel  ranges,  with  a  north  and  south  trend. 

The  central  region  is  occupied  by  what  is  known  as  the  IMojave  Desert, 
the  western  part  of  which  is  known  as  the  Antelope  Valley.  The  south- 
eastern portion  is  known  as  the  Colorado  Desert  and  the  southwestern 
(piarter  is  occupied  by  the  San  Bernardino  and  Peninsula  ranges. 

The  general  geology  and  oil  possibilities  of  this  region  may  be  sununed 
up  as  follows  (exclucling  the  small  portion  of  Riverside  and  San  Bernar- 
dino counties  wdiich  lies  west  of  the  mountains  ;ind  belongs  to  the  coastal 
area)  : 

The  greater  part  of  the  tint  desert  floor  is  covered  by  recent  sand 
deposits.  Along  the  lower  foothills  of  tlie  mountain  ranges,  particularly 
in  the  western  and  northern  portions,  there  are  small  areas  of  Tertiary 
sedimentary  rocks,  interbedded  with  lava  flows.  These  sediments,  for 
the  most  part,  represent  either  lake  or  land  deposits.  The  higher  i-anges 
of  the  southern  region  are  composed  of  crystalline  rocks,  either  granites 
or  pre-Cambrian  metamorphics.  The  high  ranges  of  the  northern  region 
are  also  crystalline  in  character,  being  either  composed  of  granites  or 
highly  metnmorphosed  sediments  of  Paleozoic  and  Mesozoic  age.  With 
two  exceptions  which  will  be  noted  below,  there  are  no  know'n  deposits 
of  sedimentary  rocks  which  may  correspond  to  the  oil-bearing  formations 
of  California.  It  is  evident  from  a  study  of  this  region  that  it  had  a 
totally  different  geological  history  from  the  oil  fields.  The  various 
Tertiary  seas  in  which  the  oil-bearing  formations  were  deposited  appar- 
ently ciid  not  cover  any  appreciable  portion  of  this  area.     The  two 


154  CALIFORNIA  STATE  MINING  BUREi^U. 

exceptions  mentioned  above  consist  of  beds  of  Eocene  age,  and  the  only 
thing  they  liave  in  common  with  tlie  oil-field  formations  is  that  they 
were  laid  down  in  the  same  sea  and  consequently  are  of  the  same  age  as 
certain  Eocene  beds  which  are  oil  bearing  in  other  portions  of  the  state. 
One  area  of  Eocene  is  fonnd  along  the  western  border  of  the  ]\Iojave 
Desert,  near  Rock  ("reek.  Los  Ang.'les  County,  and  consists,  according 
to  Dicker.son,^  of  about  5000  feet  of  coarse  sandstone  and  shale,  belonging 
to  the  Martinez  formation.  This  area  probably  represents  the  eastward 
line  of  the  ^Martinez  Sea.  The  second  area  of  Eocene  is  fonnd  in  the 
Elsinore  Valley  and  consists  of  small  thicknesses  of  highh^  colored  shales 
and  sands  of  Tejon  age.  Neither  of  these  deposits  show  the  slightest 
indication  of  petroleum.  The  rocks  that  are  present,  consisting  mainly 
of  granites,  highly  metamorphosed  Paleozoic  and  Mesozoic  sediments, 
Tertiary  sediments  of  land  or  lake  origin,  together  with  lava  flows,  are 
all  unsuitable  for  the  formation  of  any  appreciable  amount  of  petroleum. 

To  the  best  of  the  writer's  knowledge  there  are  no  known  authentic 
seepages  of  oil  in  this  area.  Two  rather  doubtful  cases  may  be  cited, 
however.  On  an  island  in'lMono  Lake  there  is  a  hot  mineral  spring  from 
which  it  is  reported  that  oil  seeps,  and  the  writer  has  been  furnished  with 
a  bottle  of  the  oil.  The  formation  in  the  vicinity  of  the  lake  and  on  the 
island  is  composed  in  part  of  fresh- water  diatomaceous  shale,  about  100 
feet  in  thickness.  This  shale  has  been  intruded  by  an  igneous  dike  and 
it  is  conceivable  that  this  intrusion  ma}'  have  caused  destructive  distilla- 
tion of  the  fresh-water  shale,  with  the  result  that  an  insignificant  amount 
of  oil  was  formed.  The  second  case  consists  of  a  sample  which  was 
brought  to  the  Bureau  by  a  prospector  from  'somewhere  near  the 
Inyo-^Iono  county  line.'  This  sample  turned  out  to  be  a  piece  of  Gil- 
sonite,  or  mineral  tar.  Deposits  of  this  tar  have  been  reported  as 
occurring  in  Nevada.  Innumerable  seepages  and  indications  of  oil  have 
been  reported  from  this  area  and  a  certain  well  in  the  ^lojave  Desert  has 
been  reporting  oil  for  the  last  eighteen  years,  but  it  may  be  noted  here 
that  in  no  case  have  these  reports  been  verified. 

From  the  above  brief  description  of  the  geology  it  is  evident  that  the 
possibility  of  obtaining  oil  in  the  desei't  region  is  extremely  small. 

Following  is  a  brief  description  of  the  particular  geology  and  at- 
tempts at  development  in  each  county : 

Mono   County. 

J\Iono  County  lies  at  the  extreme  northern  end  of  this  area.  The  for- 
mations exposed  are  mainl}'  granitic  rocks  and  lava  flows.  In  the  moun- 
tains west  of  IMono  Lake  and  in  the  southeastern  portion  of  the  county, 
reddish  gray  limestones  and  beds  of  sandy  shale  of  Cambrian  age  have 
been  reported.  In  the  vie-inity  of  Coleville,  Bridgeport  and  on  the  east 
side  of  Mono  Lake,  there  are  fresh-water  sedimentary  deposits,  probably 
representing  old  lake  beds.  At  IMono  Lake  they  contain  a  bed  of  fresh- 
water diatomaceous  .shale,  from  which  seepages  of  oil  have  been  reported, 
a  possible  explanation  of  which  has  been  given  in  the  preceding  para- 
graphs. Following  is  a  portion  of  IMcLaughlin  and  Waring 's  report  on 
this  area  :- 


'University  of  California.  BuH.  Dtpartnicnt  of  Geology,  Vol.  8,  No.  14.  The  Mar- 
tinez,  Eocene  and  Assoiiatetl   Formations  at   Rock  Creek.      By  R.   E.   Dickerson,   1914. 

=California  State  Mining  Bureau.  Bull.  69.  Fetroleum  Industry  of  California.  By 
R.  F.  McLaughlin  and  C.  A.  "Waring,  1914. 


PETKOLEUM    RESOURCES   OF    CALIFORNIA.  155 

"Mono  County 

"Attempts  have  lippn  made  to  develop  oil  near  Mono  Lake  and  a  brief  statement, 
based  upon  examinations  by  the  autlior,  of  the  very  scant  possibilities,  may  be  useful. 
Surrounding  tlie  lake  are  sedimentary  deposits  containing  marl,  clay  and  diatoms, 
volcanic  ash  and  gravel.  Israel  C.  Russell  reports'  a  measured  thickness  of  200  feet, 
and  states  that  tlie  total  must  be  very  much  greater.  This  deposit  was  laid  down 
during  Quaternary  time  when  the  lake  was  much  larger  tlian  at  present.  There  are 
no  other  unaltered  sediments  known.  The  lake  deposits  rest  upon  granite,  meta- 
morphics  and  glacial  drift  and  are  intruded  or  overflowed  by  recent  basic  igneous 
rocks. 

"The  only  reported  indications  of  oil  is  a  spring  near  the  eastern  shore  of  Paoha 
Island.  Russell  mentions  this  spring  and  the  fact  that  it  had  an  odor  of  petroleum. 
However,  he  gives  the  temperature  of  the  water  and  its  analysis,  but  makes  no 
further  mention  of  the  presence  of  oil.  Several  experienced  oil  men  have  stated 
that  they   collected   oil   on   the   surface  of   the  water. 

"During  1908  there  were  two  wells  drilled.  One,  near  Dechambau's  Ranch  on  the 
northern  shore  of  the  lake,  is  about  900  feet  deep,  and  hot  water  flows  over  the 
casing.  The  other  well,  near  the  southwestern  shore  of  Paoha  Island,  was  drilled 
to  2010  feet,  all  in  blue  shale  except  between  1700  and  1800  feet,  where  pink  sand 
gave  a  strong  flow  of  hot  water  which  rose  over  the  casing. 

"There  is  no  reason  to  suppose  that  other  drilling  would  be  successful." 

A  detailed  geological  descrii)tion  of  the  county  can  be  found  in  the 
Eighth  Annual  Report  of  the  ITnited  States  Geological  Survey,  Part  I, 
pp^.  2()l-394,  by  Israel  C.  Russell. 

Inyo   County. 

The  format ion.s  of  Inyo  County  may  l)e  divided  roughly  into  three 
classes.  The  first  consists  of  beds  of  highly  altered  sediments,  mainly 
liiiK^stones  and  slates,  vaiying  in  age  from  the  Cambrian  to  the  Triassic. 
They  are  found  in  the  mountain  ranges  east  of  the  Owens  River  Valley. 
The  .second  consists  of  great  ma.sses  of  granite,  which  have  been  intruded 
into  the  altered  sediments. 

The  third  consists  of  Tertiary  lava  flows,  lying  unconformably  upon 
the  first  two.  AH  have  been  highly  crushed  and  folded.  The  only 
area  of  unaltered  sediments  is  a  small  thickn&ss  of  Tertiary  beds  along 
the  west  fiaiik  of  the  Funeral  ]\Iouiitains,  near  Furnace  Creek.  These 
beds,  with  a  maximum  thickne.s.s  of  about  500  feet,  consist  of  tuffaceons 
.sandstone,  conglnmerates  and  clays.  H;ill-  has  correlated  them  with 
the  Siebert  lake  liods  of  ^Miocene  age.  No  evidence  of  petroleum  has 
])een  reported  from  this  fonnatiun.  A  detailed  geological  map  and 
report  of  the  county  has  been  made  by  AVaring  and  Iluguenin."- 

Eastern    Kern   County. 

This  includes  the  desert  region  of  Kern  County,  which  lies  east  of  the 
Tehachapi  jMountains  and  forms  the  northwestern  portion  of  the  Mo.jave 
Desert  and  the  Antelope  Valley. 

The  formations  exposed  con.sist  mainly  of  much  altered  schi.st,  gneisses, 
marbles  and  slates,  probably  of  Paleozoic  age,  together  with  smaller 
areas  of  granite.  Overlying  these  ancient  rocks  is  a  series  of  beds  of 
Tertiary  age,  to  which  the  general  name  of  the  Rosamond  Series  has 
been  applied  by  Iler.shey.* 

These  beds  are  found  at  wide  intervals  over  practically  all  the  Mojave 
Desert  region.     They  consist  of  beds  of  sandstone  derived  from  granitic 

'U.  S.  Geol.  Survey.      Eighth  Annual  Report.      Part  T,  pp.  261-394. 

=U.  S.  Geological  Survey.  Bull.  308.  Geologic  Reconnaissance  in  Southwestern 
Nevada  and  Eastern  California.      Ry  Sidney  H.  Ball,  1907. 

'California  State  Mining  Bureau.  Geological  Map  of  Inyo  County.  By  C.  A.  Waring. 
1917.  Mines  and  Mineral  Resources  of  Inyo  County,  1915-1916.  By  C.  A.  Waring  and 
E.  Iluguenin.      Also  in  Report  XV,  pp.  29-134. 

^Hershey,  O.  H.  Some  Tertiary  Formations  of  Southern  California.  Am.  Geologist. 
Vol.  29,  pp.  365-370,   1903. 


156  CALIFORNIA    .-STATE    MINING   BUREAU. 

debris,  together  with  beds  of  rhyolitic  tuff,  eoarse  breccias  of  lava  and 
granite  and  some  iniuhly  clay  shales.  Their  niaxiimiiu  thickness  is  about 
3000  feet  and  the  age  is  upper  ^lioeeiie.  They  contain  no  evidence  of 
petroleum.  Within  the  area  under  discussion  they  are  found,  just  north 
of  Kosamond  Station,  and  in  the  El  Paso  Range,  near  Rieardo  post 
otfice.  It  is  also  possible  tliat  they  ontero])  in  the  hills  north  of  Neenach, 
in  the  Antelope  \'allev. 

In  See.  27,  T.  9  N.,  R.  17  W.,  S.  B.  B.  and  :M.,  about  six  miles  northwest 
of  the  ridge  route  of  the  state  highway,  there  is  a  well  being  drilled  by 
Robert  AVatcborn.  A  depth  of  4100  feet  has  been  reached,  at  which  point 
a  large  tlow  of  hot  mineral  water  was  encountered.  The  well  is  located 
just  south  of  an  area  of  crystalline  rocks  and  the  material  around  the 
rig  consists  of  granitic  debris.  It  is  possible  that  the  well  was  drilled  for 
a  portion  of  the  way  in  the  Rosamond  Series. 

Northeastern    Los   Angeles   County. 

This  comprises  that  portion  of  Los  Angel(\s  County  lying  north  of  and 
inchuling  the  north  Hank  of  the  Sierra  Liebre  and  San  Gabriel  ranges. 
The  level  portion  of  this  area  is  known  as  the  Antelope  Valley  and  is 
covered  by  recent  desert  deposits.  Along  the  eastern  line  of  the  county 
there  are  outcrops  of  crystalline  rocks.  The  north  flank  of  the  San 
Gabriel  and  Sierra  Liebre  ranges  are  composed  mainly  of  granite,  with 
smaller  areas  of  metamorphic  rocks.  At  various  places  along  the 
southern  edge  of  the  Antelope  Vallej'  there  are  small  patches  of  unaltered 
Tertiary  deposits.  These  consist  of  coarse  sandstone  conglomerates  and 
clays,  partly  old  lake  beds  and  partly  landlaid  deposits.  The  age  is 
mainly  IMiocene.  The  only  marine  deposit  recognized  consists  of  the 
area  of  ]\Iartinez  Eocene,  reported  by  Uickerson  at  Rock  Creek  and 
referred  to  at  the  beginning  of  the  chapter. 

It  is  possible  that  beneath  tlie  recent  desert  sands  there  are  present 
beds  of  the  Rosamond  Series.  Nowhere  in  the  district  is  there  any 
evidence  of  petroleum. 

San    Bernardino   County. 

Practicalh'  nine-tenths  of  the  county  lies  north  of  the  San  Bernardino 
]\rountains  and  forms  the  greater  portion  of  what  is  known  as  the  Mojave 
Desert  region.  The  flat  desert  spaces  of  this  region  are  covered  with 
recent  desert  deposits.  The  mountain  ranges  are  composed  of  crystalline 
and  highly  altered  metamorphic  rocks.  These  consist  of  granitic  rocks, 
areas  of  metamorphosed  sediments  of  pre-Cambrian  and  Paleozoic  age, 
together  with  lava  flows,  mainly  of  Tertiary  age.  There  are  also  in 
various  basins,  beds  of  coarse  sand,  conglomerates  and  clays,  representing 
lake  and  landlaid  deposits  of  Tertiary  and  Quaternary  age. 

In  the  region  around  Barstow  and  Daggett,  extensive  areas  of  the 
Rosamond  Series  (upper  Pliocene)  have  been  recognized.  The  Rosamond 
beds  are  here  composed  of  lava  flows,  fine-grained  tuff,  volcanic  ash, 
beds  of  green  clay,  conglomerate,  impure  limestone,  and  coarse  sand- 
stone, none  of  which  are  ca{)able  of  forming  any  amount  of  petroleum. 
Nevei'tlu'U'ss,  a  superficial  I'cscmblance  of  certain  of  the  clay  beds 
to  some  of  the  oil  field  formations  has  caused  periodic  "oil  booms'  in  this 
region  for  the  last  eighteen  years.     Seepages  and  oil  showing  in  wells 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  157 

(Irilk'd  here  liave  been  reported  but  never  veritieil.  Tlie  area  has  been 
examined  by  the  rnited  States  Geobt'Jrii-al  Survey^  for  oil  and  has  been 
condemned. 

Following  is  Pack's  eonelusion  of  the  region: 

"CONCLUSIONS  AS  TO  THE  PRESENCE  OF  PETROLEUM. 

"The  writer  believes  that  the  northern  part  of  the  Mojave  Desert  between  Barstow 
and  the  town  of  Mojave  offers  practically  no  promise  of  becoming  a  productive  oil 
field,  and  that  further  drillinK  will  prove  but  a  waste  of  money.  The  principal 
reasons  for  believing  that  this  land  will  not  prove  productive  are  (1)  the  lack  of 
strata  from  which  it  would  seem  reasonable  to  believe  that  oil  might  have  been 
formed,  especially  the  lack  of  thick  masses  of  organic  material  (diatomaceous  and 
foraminiferal  shale),  such  as  those  which  occur  in  or  near  all  the  oil  fields  in  the 
southern  half  of  California,  and  in  which  the  oil  is  believed  to  have  originated;  (2) 
the  lack  of  structural  features  favorable  for  the  correction  of  petroleum,  even  if  it 
existed,   disseminated  tlirough  the   strata. 

"Tile  pre-Tertiary  rocks  can  not  reasonably  be  regarded  as  a  source  of  petroleum. 
Only  a  small  portion  of  these  rocks  are  of  sedimentary  origin,  and  they  are  so 
metamorpliosed  that  ev<>n  had  oil  once  existed  in  them  it  is  hardly  conceivable  that 
they  should  still  contain  it.  The  granitic  rocks  in  the  complex  are,  if  possible,  an 
even  less  likely  source  of  petroleum,  as  their  texture  is  so  dense  that  they  would  offer 
practically  no  reservoir  in  which  oil  might  collect  if  it  existed  in  the  near-by  rocks. 
Oil  has  been  found  in  rocks  lithologically  similar  to  some  of  the  pre-Tertiary  rocks  of 
the  Mojave  Desert  at  only  a  single  locality  in  California.  This  occurrence,  at 
Placerita  Canyon,  about  20  miles  north  of  Los  Angeles,  has  been  described  by 
Eldridge=.  The  oil,  at  this  place,  occurs  in  fractui-ed  schists  which  rest  upon  the 
granite  of  the  San  Gabriel  Mountains.  The  most  logical  explanation  for  the  presence 
of  the  oil  here  is  that  it  has  migrated  from  early  Tertiary  organic  shales  which  may 
have  at  one  time  rested  upon  the  metamorphic  rocks,  and  which  may  now  occur  in 
the  vicinity  beneath  the  unconformably  overlying  late  Tertiary  beds.  In  the  Santa 
Clara  River  Valley,  a  few  miles  west  of  Placerita  Canyon,  the  early  Tertiary  strata 
and  the  beds  in  contact  with  them  are  filled  wMth  oil.  As  organic  materials  similar 
to  those  in  the  Santa  Clara  Valley  are  unknown  in  the  Barstow-Kramer  region, 
it  can  not  be  expected  that  a  similar  accumulation  of  oil  will  be  found  in  the 
metamorphic  rocks  in   this  region. 

"The  lecent  coarse  gravel,  sand  and  clay  which  form  the  filling  in  the  topographic 
basins  and  which,  in  places,  extend  as  a  veneer  over  the  lower  hills,  are  equally  as 
unlikely  a  source  of  petroleum  as  the  pre-Tertiary  complex.  They  are  composed 
almost  or  quite  complete  of  fragments  derived  from  the  older  rocks  in  this  or  in 
adjacent  resions.  and  it  is  not  reasonable  to  believe  that  these  masses  of  rock 
fragments  would  be  more  likely  to  produce  petroleum  than  the  same  rocks  in  place. 
The  Tertiary  volcanic  rocks  are  likewise  not  to  be  considered  as  a  source  of  petroleum 
for  much  the  same  reasons  as  apply  to  the  granitic  rocks  in  the  pre-Tertiary 
complex. 

"It  remains  then  but  to  consider  the  Tertiary  sedimentary  rocks.  The  coarse- 
gi-ained  Tertiary  beds  are  formed  of  fragments  of  various  types  of  granitic,  volcanic, 
and  metamorphic  rocks  and  are  evidently  no  more  probable  a  source  of  petroleum 
than  pre  the  recent  beds  of  sand  and  gravel.  On  the  other  hand,  to  casual  observa- 
tion, the  fine-grained  Tertiary  rocks  of  the  Barstow-Kramer  region  appear  to  be 
similar  to  the  Tertiary  rocks  in  many  of  the  oil  fields  of  this  state,  and  it  is  not  so 
very  surprising  that  in  this  region  they  have  been  regarded  as  a  possible  source  of 
oil.  A  careful  examination  of  them  shows,  however,  th.at  they  are  really  very 
different  from  the  Tertiary  shales  in  the  productive  oil  fields,  and  in  place  of  being 
composed  very  largely  of  the  remains  of  organisms  they  are  formed  almost  wholly 
either  of  fine  volcanic  ash  or  of  detrital  material  derived  from  rocks  of  v.arious 
types.  They  thus  resemble  the  coarse-grained  beds  in  the  same  region,  differing 
from  those  beds  mainly  in  the  size  of  the  particles  they  contain,  and  are  not  to  be 
compared  with  the  masses  of  organic  material  in  the  large  productive  oil  fields  of 
California.  The  only  indications  of  organic  matter  seen  in  these  beds  were  small 
particles  of  carbonized  terrestrial  vegetation  scattered  through  some  of  the  clayey 
and  finer  sandy  beds,  but  the  total  amount  of  organic  matter  is  entirely  too  small  to 
be  considered  as  a  possible  source  of  more  than  the  merest  traces  of  oil. 

"It  is,  of  course,  possible  that  in  the  broad,  level  desert  areas,  rocks  of  diffe'-ent 
types  from  any  exposed  in  the  hills  may  lie  buried  beneath  the  desert  gravel.  It  is 
also  possible  that  .=uch  rocks,  if  they  occur,  are  like  those  in  the  Tertiarv  formations 
in  the  San  Joaquin  Valley  on  the  opposite  side  of  the  Tehachapi  Mountains.  There  is, 
however,  nothing  in  the  geology  of  this  region,  or,  so  far  as  known.  In  that  of  the 
desert  as  a  whole,  to  support  such  a  hypothesis. 

"No  surface  indication  of  petroUum  was  seen  anywhere  in  the  region.  It  is 
commonly  rumored  that  a  seep  occurs  in  the  Tertiary  rocks  northwest  of  Black 
Mountain,  but  a  careful  search  failed  to  reveal  it  nor  did  persistent  questioning 
discover  anyone  who  could  describe  its  location.     The  structure  of  the  Tertiary  rocks 

^U.  S.  Geol.  Survey.  Bull.  541.  Reconnaissance  of  the  Barstow-Kramer  Region  By 
R.  W.  Pack.  1914.  ■        " 

=Eldridge,  G.  H.,  and  Arnold.  Ralnii.  The  Santa  Clara  Valley,  Puente  Hills  and  Los 
Angeles  Oil  Districts,  Southern  California.  U.  S.  Geol.  Survey.  Bull.  309.  Pp.  100- 
101,   1907. 


158  CALIFORNIA    STATE   MINING   BUREAU. 

is  complex.  In  many  places  they  are  tilted  to  high  angles  and  iiitiieatoly  faulted, 
and  if  oil  oceiiis  in  them  it  is  surprising  that  it  does  not,  at  some  place,  show  at 
the  surface. 

"Even  if  oil  was  oiigiiially  disti-ibiited  in  minute  quantities  through  the  rocks,  the 
structure  is  not  such  tliat  it  would  have  tended  to  collect  or  trat)  the  oil.  Irregular 
and  faulted  folds  occur  in  at  least  three  places  northwest  of  Barstow — the  Barstow 
syncline  in  T.  11  N.,  R.  2  W..  a  small  anticline  just  noith  of  the  Glroux  well  in  T.  32 
S.,  R.  44  B..  and  an  irregular  fold  or  folds  in  T.  31  S.,  R.  44  B.  It  is  generally 
reported  that  a  well-marked  anticline  passes  through  the  hills  north  of  Barstow. 
Indeed,  it  is  believed  by  some  that  such  a  fold  extends  along  the  north  side  of  the 
desert  from  Tehachapi  Pass  nearly  to  Barstow.  This  idea  is  erroneous,  for  the  only 
fi>lds  here  are  small,  discontinuous  and  much  faulted.  Faults,  not  folds,  dominate 
the  structure.  Thus  the  structure  is  much  more  favorable  for  the  escape  of  any  oil 
that  might  possibly  have  been  found  here  than  it  is  for  its  concentration  in 
appreciable  quantities." 

Four  wells  have  l)een  drilled  here.  The  Kramer  Consolidated 
Oil  Company's  well  in  the  NW]  of  See.  11,  T.  10  N.,  R.  5  W.,  is  located 
ahoiit  three  miles  north  of  ITawes  Station,  on  the  Santa  Fe  Railroad. 
This  well  has  })een  drilling  for  the  last  18  years,  and  a  depth  of  3000 
feet  has  been  reached.  The  Chicago  Oil  Company's  well  in  the  SW^ 
of  Sec.  35,  T.  11  N.,  R.  1  W.,  is  located  on  the  west  side  of  the  Calico 
IMountains,  and  a  depth  of  over  2000  feet  is  reported. 

The  Giroux  well  in  the  SEj  of  Sec.  17,  T.  32  S.,  R.  4  E.,  is  located 
a  mile  w^est  of  Black  Canyon.     A  depth  of  440  feet  is  reported. 

The  Mojave  Oil  Company's  well  in  the  SEj  of  Sec.  14,  T.  11  N., 
R.  12  W.,  is  located  about  2|-  miles  southeast  of  Mojave.  A  depth  of 
1100  feet  is  reported. 

In  Cajon  Pass,  and  in  the  region  north  and  west  of  the  Paso,  there 

is  an  area  of  highly-tilted  deposits  consisting  of  fangloraerates,  coarse 

conglomeratic  sandstone,  clays  and  shales.     Dickerson^  believes  these 

to  be  of  upper  IMiocene  age,  and  to  represent  lake  and  land-laid  deposits. 

The  San  Bernardino  IMountains  consist  mainly  of  granitic  rocks, 
together  with  smaller  areas  of  highly  altered  cry.stalline  sediments  of 
Paleozoic  age. 

District   Lying   West  of  the  San    Bernardino    Mountains. 

This  district  comprises  the  fertile  valley  land  lying  in  the  vicinity 
of  Redlands,  San  Bernardino  and  Chino.  On  the  north  and  northeast 
it  is  bounded  by  crystalline  rocks  of  the  San  Gabriel  and  San  Ber- 
nardino ranges;  on  the  east  and  southeast  it  extends  into  Riverside 
County  for  a  few  miles,  where  it  is  terminated  by  crystalline  rocks 
of  the  Peninsula  Range.  At  the  extreme  southwest  corner  lie  the  Chino 
Hills,  compDscd  of  sedimentary  rocks  of  Tertiary  age.  The  greater 
portion  of  this  area  is  covered  by  recent  soil  and  valley  alluvium,  but 
it  is  probable  that  the  crystalline  rocks  which  bound  it  on  three  sides 
are  present  at  no  great  depth  beneath  this  surface  soil.  There  are  two 
areas  of  unaltered  sedimentary  rocks  within  this  district.  One  lies  south 
of  Redlands,  and  is  composed  of  light-colored  clays  and  shale,  together 
with  beds  of  gravel.  These  beds  are  continuous  with  similar  beds  in 
the  vicinity  of  Beaumont  and  San  Gorgonio  Pass,  and  will  be  discussed 
more  fully  under  the  article  on  Riverside  County.  It  can  be  noted 
here,  however,  that  they  contain  no  indication  of  petroleum.  The 
second  area  of  sedimentary  rocks  lies  in  the  Chino  Plills.     This  is  the 


^University  of  California.  Department  of  Geology.  Bull.  14,  Vol.  S.  The  Martinez, 
Bocene  and  Associated  Formations  at  Rock  Creek  on  the  Western  Border  of  the 
Mojave  Desert.     By  Roy  E.  Dickerson,   1914. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  159 

only  portion  of  San  B<'rnardino  County,  or  of  the  entire  region  under 
(liscnssion  in  this  ehiiplcr.  tliat  offers  the  slightest  possibility  of  con- 
taining oil.  These  liills,  \vhi»  h  lie  to  the  south  and  west  of  Chino, 
are  the  northeast  portion  of  the  Puente  Hills  of  Los  Angeles  County, 
but  are  known  locally  as  the  Chino  Hills.  The  formations  exposed 
consist  mainly  of  sandstone  and  diatomacoous  shale  belonging  to  the 
lower  portion  of  tlie  ^lonteri^y  Series,  which  is  known  in  this  locality 
as  the  Puente  formation.  At  the  extreme  south  end  of  this  area,  along 
the  Santa  Ana  River,  the  lower  Puente  is  overlaid  by  a  small  area  of 
Fernando.  The  diatomaceous  shale  of  the  Puente  is  the  source  of  the 
oil  in  the  proven  fields  of  Los  Angeles  and  Orange  counties,  and  within 
the  area  under  discussion  it  contains  indications  of  oil.  These  consist 
of  numerous  outcrops  of  oil  sand  and  bituminous  shale.  The  general 
structure  consists  of  a  monocline  dipping  to  the  northeast  in  which 
there  are  minor  anticlinal  folds. 

The  region  can  not  be  considered  as  favorable  for  the  accumulation 
of  oil  in  commercial  quantities.  This  is  due  to  the  lack  of  reservoir 
beds  overlying  the  Puente,  and  to  the  general  unfavorable  structure. 

There  have  been  a  number  of  wells  drilled  in  this  region,  the  majority 
of  which  encountered  small  showings  of  heavy  tar  in  the  sandstone 
beds  of  the  Puente,  but  failed  to  produce  on  a  commercial  scale. 
There  is  no  reason  to  believe  that  wells  drilled  here  in  the  future  would 
have  any  better  results. 

Following  is  a  list  of  the  abandoned  wells: 

The  Chino  Land  and  Water  Company's  wells  were  located  on 
See.  32,  T.  2  S.,  R.  8  W.,  and  encountered  heavy  oil  between  900  and 
1000  feet.  The  Chino  Valley  Beet  Sugar  Company's  wells  were 
located  on  Sec.  30,  T.  2  S.,  R.  8  AV.,  and  encountered  heavy  tar 
between  450  and  465  feet. 

At  the  present  time  the  following  wells  are  drilling  in  this  area: 

The  International  Petroleum  Company's  well  is  located  on  Sec,  17, 
T.  2  S.,  R.  8  AV. ;  The  Pomona  Petroleum  Companv's  well  is  located  in 
Sec.  28,  T.  2  S.,  R.  8  W.;  The  Chino-Corona  United  Companv's  well  is 
in  See.  1,  T.  3  S.,  R.  8  W.  The  Mahala  Oil  and  Gas  Company's  well  is 
in  Sec.  13,  T.  3  S.,  R.  8  W.  All  of  these  wells  have  reported  showings 
of  heavy  oil. 

Riverside   County. 

The  eastern  half  of  the  county,  lying  east  of  the  Salton  Sink  area,  is 
a  mountainous  and  desert  region,  commonly  known  as  the  Colorado 
Desert.  The  chief  mountain  ranges  are  the  San  Bernardino  Range 
and  the  Hathaway  and  Chuckawalla  mountains.  The  level  desert  area.s 
are  covered  by  recent  sand,  while  the  mountain  ranges  are  composed  of 
crystalline  rock,  chietly  granites  and  ancient  metamorphic  sediments. 
On  the  west  slope  of  tlie  Hathawa.y  ^Mountains,  bordering  the  Salton 
Sea,  Pliocene  beds  of  red  and  white  clay  and  gravel  are  reported. 
They  apparently  contain  no  evidence  of  petroleum  and  are  probably 
not  of  marine  origin. 

Along  San  Gorgonio  Pass,  from  Whitewater  to  Redlands,  there  are 
outcrops  of  gritty  clay  shales  and  gravels,  probably  of  Pliocene  age. 


160  CALIFORNIA    8TATE   MINING   BUREAU. 

The  total  areal  extent  of  these  l)e(ls  is  al)out  36  miles  in  length  from 
east  to  Avest,  and  about  12  niih's  in  width  from  north  to  south.  Small 
patches  of  the  same  formation  are  found  in  tlie  hills  east  of  liemet 
and  alonof  the  north  side  of  Temeeula  Cici-k  in  tlic  vieinity  of  ^lurrietta 
and  Temeeula.  In  all  of  these  localities  tliey  lie  on  tlie  eroded  surface 
of  the  uiulerlyins'  crystalline  rocks. 

These  beds  can  not  be  ccusid(  red  as  oil  bearing.  This  statement  is 
based  on  the  following  facts:  They  contain  absolutely  no  indication 
of  oil,  such  as  seeps,  or  gas  blows ;  they  contain  no  diatomaceous  shale, 
or  other  organic  material  that  is  capable  of  forming  oil;  their  total 
areal  extent  and  thickness  is  such  that  even  if  they  did  contain  organic 
material,  the  amount  of  oil  capable  of  being  formed  would  be  negligible. 
Lastly,  it  is  doubtful  that  they  are  of  marine  origin,  it  being  probable 
that  they  I'cpi-esent  laud-laid  desert  dei)osits.  Nevertheless,  the  follow- 
ing wells  are  being  drilled  in  this  region:  Riverside  County  Oil  Com- 
pany well  No.  1  in  Sec.  12,  T.  2  S.,  R.  1  W. ;  Painted  Hills  Oil  Syndi- 
cate well  No.  1,  Sec.  25,  T.  2  S.,  R.  3  E. ;  Beaumont  Crude  Oil  Company 
well  No  1  in  Sec.  15,  T.  3'S.,  R.  1  W. ;  ^Moreno  Oil  Company  well  No.  1, 
Sec.  15,  T.  3  S.,  R.  2  W. ;  Neuvo  Oil  Company  well  No  1,  Sec.  26,  T.  3 
S.,  R.  7  W. 

That  portion  of  the  county  lying  south  from  San  Gorgonio  Pass  to 
the  San  Diego  and  Orange  county  lines,  is  a  mountainous  region  of  the 
Peninsula  Range.  It  contains  two  rather  flat  areas,  one  known  as  the 
San  Jacinto  Basin,  and  the  other  as  the  Temeeula  Basin.  The  moun- 
tains in  the  northern  portion  are  known  as  the  San  Jacinto  JNIountains, 
while  those  south  of  Temeeula  Creek  are  known  as  the  Santa  Ana 
JMountains.  The  major  portion  of  this  region  is  covered  with  crystal- 
line rocks,  consisting  of  granites,  lava  flows  and  ancient  slates  and 
schists,  probably  of  Triassic  age.  None  of  these  rocks,  of  course,  are 
capable  of  containing  oil.  Around  Hemet,  Temeeula  and  Murritta 
are  the  deposits  of  shales  and  gravels  of  Pliocene  age  referred  to  in 
the  preceding  paragraphs.  Along  Temeeula  Wash,  between  Elsinore 
and  Corona,  there  are  approximately  five  small  patches  of  rocks  of 
Eocene  age,  which  are  lying  on  the  eroded  surface  of  the  underlying 
crystalline  rocks.  These  consist  of  red,  yellow  and  white  clays,  con- 
taining beds  of  lignite  and  probably  belonging  to  the  Tejon  formation. 
They  seldom  cover  a  square  mile  in  extent,  and  the  maximum  thickness 
is  about  600  feet.  They  show  no  evidence  of  petroleum.  A  well 
drilled  for  oil  in  1915,  located  about  a  mile  east  of  Lucerne,  encountered 
the  following  formations:  0  to  250',  gravel  and  conglomerate,  probal)ly 
Pliocene;  250'  to  927',  clays  and  shales,  probably  of  Tejon  age;  at  927' 
crystalline  rocks  were  encountered. 

In  the  valley  area  between  Corona  and  Riverside,  forming  the 
extreme  southwestern  end  of  the  county,  the  surface  is  covered  mainly 
with  recent  valley  alluvium.  But  it  is  probable  that  this  is  underlaid 
at  no  great  depth  by  crystalline  rocks,  especially  that  portion  of  the 
area  lying  east  of  the  Santa  Ana  River.  In  .several  places  the  granite 
actually  outcroi)s  in  low  rounded  buttes.  Along  both  banks  of  the 
Santa  Ana  River,  in  the  vicinity  of  Rincon  and  where  the  river  crosses 


PETROLEUM    RESOURCES   OP    CALIFORNIA.  161 

the  boundary  line  into  Orange  County,  there  are  outcrops  of  Monterey 
shale  (Puente)  and  Fernando  sandstone.  These  formations  are  con- 
tinuations of  similar  beds  in  the  Chino  Hills  region  and  described  in 
the  article  on  San  Bernardino  County. 

The  total  ai'cal  extent  tliat  these  bed.s  cover  in  Riverside  County  is 
not  over  four  square  miles.  While  they  belong  to  the  oil-bearing  series, 
there  is  no  evidence  that  they  would  produce  any  appreciable  amount 
of  oil  in  this  region.  It  is  barely  possible  that  tliey  iiiiiiht  contain 
some  dry  tar  sands.  Two  wells  are  being  drilled  in  this  general  region, 
the  N.  B.  Tannehill  well  in  Sec.  35,  T.  2  S.,  R.  7  AV.,  and  the  Corona 
Oil  Company's  well  in  Sec.  2,  T.  3  S.,  R.  7  W.  These  wells  are  located 
about  four  miles  north  of  Corona  and  about  three  miles  from  the 
granite  buttes. 


11—13322 


162  CALIFORNIA    STATE    MINING   BUREAU. 


CHAPTER  XIII. 


Region  of  the  San  Joaquin  Valley. 

(Includes  the  following-  counties:  San  Joaquin,  Stanislaus,  Merced,  the  western 
one-thii'd  of  Madera,  the  western  two-thirds  of  Fresno,  Kings,  the  western 
half  of  Tulare  and  Kern.) 

The  region  of  the  San  Joaquin  Valley  contains  the  chief  producing 
fields  of  California.  These  are  found  along  the  west  side  of  the  valley 
from  Coalinga  to  Sunset,  and  on  the  east  side  in  the  region  immediately 
about  Bakersfield. 

In  addition  to  containing  the  chief  proven  areas  of  the  state,  the 
valley  may  be  regarded  as  offering  the  best  opportunities  for  future 
development.  These  inchide  not  only  the  development  and  extension 
in  the  already  proven  areas,  but  also  include  the  possibility  of  discover- 
ing new  fields  buried  beneath  the  surface  soil  of  the  valley  floor. 

GENERAL  GEOLOGY  OF  THE  VALLEY. 

The  principal  formations  which  are  exposed  consist  of  approximately 
20,000  feet  of  nnaltered  sediments  of  Tertiary  age,  ranging  from  the 
Eocene  to  the  late  Pliocene.  These  ai'e  overlaid  by  small  thicknesses 
of  recent  Quaternary  deposits.  On  the  east  and  south  sides  of  the 
valley  these  sediments  rest  against  the  crystalline  rocks  of  the  Sierra 
Nevada,  Tehachapi,  and  San  Emigdio  mountains.  On  the  west  they 
rest  on  the  eroded  surface  of  the  older  Cretaceous  and  Franciscan 
rocks  of  the  Coast  ranges.  It  is  very  probable  that  during  the  greater 
portion  of  the  Tertiary  period  the  valley  was  a  great  inland  sea,  the 
eastern  and  sonthern  edges  being  marked  approximately  by  what  is 
now  the  Sierra  Nevada,  Tehachapi,  and  San  Emigdio  mountains,  while 
the  present  Coast  ranges  were  a  series  of  islands.  Twice  during  this 
period  were  great  thicknesses  of  organic  sediments  deposited  and  these 
beds  may  be  considered  as  the  ultimate  source  of  the  greater  portion 
of  the  oil  now  being  produced  in  the  valley. 

The  oldest  of  these  formations  is  of  Oligocene  age  and  is  known  as 
the  Kreyenhagen  shale.  It  consists  of  approximately  1500  feet  of  pink 
diatomaceons  and  foraminiferal  shale.  The  area  occupied  by  this 
formation  may  be  considered  as  lying  along  the  western  side  of  the 
valley  from  approximately  the  vicinity  of  Tulare  Lake  north  to  the 
vicinity  of  the  northwestern  boundary  of  Stanislaus  County.  This 
shale  is  the  source  of  the  greater  portion  of  the  oil  produced  in  the 
Coalinga  field. 

The  second  deposit  of  organic  shale  of  the  Tertiary  period  is  of 
Miocene  age  and  consists  of  nearly  5000  feet  of  diatomaceons  shale 
belonging  to  the  Monterey  and  Santa  IMargarita  series.  The  area 
occupied  by  it  may  be  regarded  as  covering  the  entire  southern  end  of 
the  valley  south  of  Tulare  Lake.  This  ]Mioeene  shale  is  the  source  of 
the  oil  in  the  Sunset,  IMidway,  Elk  Hills,  INIcKittrick,  Belridge,  Lost 
Hills  and  Kern  River  fields.  From  the  above  it  is  evident  that  the 
productive  areas  of  the  San  Joaquin  will  be  in  the  districts  occupied 
by  these  two  deposits  of  organic  shale. 


PETROLEUM    RESOURCES   OF    CAIJFORXIA.  163 

In  addition,  diu-ing  the  Cretaceous  period,  there  was  an  older  body  of 
organic  shaU;  deposited  belon^inp:  to  the  Chico  f(»niiation  and  known 
as  the  ^Moreno  shale.  Tliis  consists  of  about  2tlOO  i'eet  of  diatoniaceous 
and  foraminiferal  shale  and  occupies  an  area  along  the  foothills  of 
the  Coast  ranges  from  Coal  in  ga  north  to  Livermore  Pass.  It  is  the 
source  of  the  small  amount  of  light-green  Cretaceous  oil  produced  in 
the  old  Oil  City  field  at  Coalinga.  It  is  important  only  in  the  Coalinga 
district  and  even  then  it  fails  to  i)n)(1u(e  an  aii})r('eial)le  percentage  of 
the  output. 

The  reservoir  formations  in  which  the  Tertiary  oil  has  collected 
consist  mainly  of  porous  sandstone  l)eds  which  overlie  the  two  shale 
deposits.  In  the  case  of  the  Kreycuhagen  shale  the  so-called  Vaciueros 
sandstone  at  Coalinga  acts  as  the  reservoir  from  which  the  oil  is 
produced.  The  oil  from  the  ^Monterey  and  Santa  ^largarita  shales  has 
collected  mainly  in  the  porous  sandstone  beds  of  the  ]\IcKittrick  group. 
Some  of  the  oil.  however,  is  found  in  sandy  beds  within  the  organic  shale 
deposits,  this  being  the  case  at  the  Lost  Hills  and  Bclridge  fields  in  the 
deep,  light  gravity  oil  zone. 

STRUCTURE. 

The  general  structure  of  the  San  Joaquin  Valley  is  that  of  a  great 
syncline,  lying  between  the  Sierra  Nevada  favdt  block  in  the  east  and 
the  anticlinorium  of  the  Coast  ranges  on  the  west.  Within  this  great 
syncline,  however,  there  are  series  of  anticlinal  folds  which  are  marked 
on  the  surface  in  most  cases  by  low  rolling  hills.  These  are  found 
mainly  along  the  western  side  of  the  valley  and  for  the  most  part 
project  obliquely  out  into  the  valley  from  the  main  body  of  the  Coast 
ranges.  In  some  cases,  however,  these  structures  lie  out  in  the  valley 
floor  and  run  parallel  to  the  Coast  ranges,  such  as  the  folds  of  the  Lost 
Hills  and  Elk  Hills  fields.  In  some  cases,  also,  there  is  no  evidence  of 
these  structures  on  the  surface  as  is  exemplified  by  the  buried  anticline 
of  the  Bclridge  field. 

It  is  on  these  folds  that  the  oil  has  been  trapped  and  collected  and 
the  proven  fields  are  located.  All  of  these  structures  that  are  at  all 
evident  have,  with  one  exception,  been  drilled  upon  and  found  pro- 
ductive. It  is,  therefore,  necessary  if  new  fields  are  to  be  found,  that 
other  structures  which  are  not  at  present  known,  be  discovered.  Such 
structures  in  all  probability  exist,  buried  beneath  the  floor  of  the 
valley  with  the  greater  portion  of  the  surface  evidence  of  their  existence 
removed  by  erosion.  This  possibility  will  be  discussed  in  the  following 
paragraphs  under  "Buried  Structures." 

The  one  exception  referred  to  above  consists  of  the  great  Kettlemen 
Hills  anticline.  This  fold,  to  date,  remains  to  be  proved  as  containing 
oil  in  commercial  quantities. 

BURIED    STRUCTURES. 

As  stated  above,  the  chief  hope  of  finding  new  fields  in  the  San 
Joaquin  Valley  lies  in  the  possibility  of  locating  structures  which  are 
buried  beneath  the  surface  soil  of  the  valley.  One  such  fold  was  dis- 
covered when  the  Belridge  field  was  found  productive.     At  the  present 


164  CALIFORNIA    STATE    MINING   BUREAU. 

an  area  around  Button  willow,  which  apparently  shows  some  evidence 
of  containing  a  buried  anticline,  is  being  tested  and  with  encouraging 
results  to  date,  such  as  c|uantities  of  gas  and  small  showings  of  oil. 
As  stated  above,  there  is  little  or  no  evidence  of  these  buried  structures 
on  the  surface,  in  the  form  of  outcrops  of  rocks  or  low  hills,  such  as 
mark  the  already  proven  areas.  The  chief  surface  evidence  that  might 
be  present  would  be  slight  elevati(»ns  and  ridges  that  rise  above  the 
dead  level  of  the  valley  floor.  Also  some  evidence  might  be  furnished 
by  water  wells  and  prospect  holes. 

It  is  evident  that  these  folds  will  be  found  only  by  a  close  study  of 
the  topography  and  logs  of  water  wells  within  the  region  in  which  they 
are  likely  to  occur. 

The  general  area  in  which  the  writer  believes  these  structures  are 
likely  to  be  found  in  the  San  Joacjuin  Valley  is  in  the  districts  referred 
to  above  as  being  underbid  by  the  organic  shale  beds  of  the  Kreyenhagen, 
Monterey  and  Santa  Margarita  formations,  namely  an  area  along  the 
west  side  of  the  valley,  running  from  the  vicinity  of  the  northwestern 
boundary  of  Stanislaus  County  southward  to  Tulare  Lake,  and  a  second 
area  comprising  the  entire  floor  of  the  valley  lying  south  of  Tulare  Lake. 
In  the  first  area  the  oil  would  ])e  formed  from  the  Kreyenhagen  sliale 
and  collect  in  the  Vacpieros  sandstone.  In  the  second  area  the  oil  would 
form  in  the  Miocene  shales  and  collect  in  the  McKittrick  beds.  Fig  12 
shows  two  hypothetical  sections  across  the  valley.  Section  AB  in  the 
region  north  of  Coalinga  and  Section  CD  in  the  area  south  of  Tulare 
Lake.  These  two  sections  show  the  possible  source  and  reservoir  beds 
in  each  district,  as  well  as  two  kinds  of  possible  accumulation — a  possible 
anticlinal  fold,  shown  in  the  left  half  of  the  sections,  and  in  the  right 
half  a  possible  monoclinal  structure  along  the  old  shore  line  of  the  sea 
in  which  the  diatomaceous  shales  were  deposited,  and  where  the  oil  might 
accumulate  by  reason  of  a  possible  overlap  of  the  reservoir  bed  on  the 
upturned  edges  of  the  shale. 

These  two  areas  have  been  shown  on  Plate  I,  colored  in  blue,  as  pos- 
sible oil  land.  This  does  not  mean  that  oil  fields  are  going  to  be  found 
over  this  entire  region,  or  for  that  matter,  that  any  will  be  found.  It 
simply  indicates  that  within  this  region  there  is  a  fairly  good  chance 
that  buried  productive  structures  may  be  found. 

REGION    OF   THE    PROVEN    FIELDS. 

The  proven  fields  of  the  San  Joaquin  may  be  divided  into  three  general 
groups.  One,  those  fields  lying  along  the  west  side  of  the  valley  from 
Sunset  to  Lost  Hills  and  commonly  known  as  the  "West  Side  Fields"; 
second,  the  Coalinga  field;  and  third,  the  Kern  River  field,  commonly 
known  as  the  "East  Side  Field." 

THE   WEST   SIDE    FIELDS. 

These  begin  at  Sunset  and  stretch  north  in  an  almost  unbroken  line  of 
derricks  to  Lost  Hills,  a  distance  of  nearly  fifty  miles.  In  these  fields 
the  oil  has  had  its  source  in  the  diatomaceous  shale  of  the  IMonterey  and 
Santa  Margarita  formations,  and  has  accumulated  mainly  in  the  over- 
lying sandstone  beds  of  the  IMcKittrick  group.  Exceptions  to  this  are 
found  in  the  Lost  Hills  and  Belridge  fields  and  in  the  Twenty-five  Hill 


PETROLEUM    RESOURCES   OF    CALIFORNIA. 


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166  CALIFORNIA    STATE   MINING   BUREAU. 

area  at  Taft,  where  some  of  the  oil  has  collected  in  the  sandy  beds  of 
the  Miocene  diatomaceons  shale  and  has  given  rise  to  the  so-called 
''shale  oil."  Also  at  Sunset,  on  the  Pioneer  anticline,  some  oil  has  col- 
lected in  the  Vaqueros  sandstone. 

MIDWAY-SUNSET. 

The  Midway-Sunset  area  is  generally  considered  as  one  field,  which 
stretches  in  an  unbroken  line  of  production  from  Sunset  to  a  point  three 
miles  north  of  Shale,  a  total  distance  of  nearly  twenty  miles.  The 
southern  portion  is  known  as  tlie  Sunset  district  and  the  northern 
portion  as  the  jNIidvvay  district. 

The  Sunset  district  lies  at  the  extreme  southern  end  of  the  valley  and 
may  be  considered  as  embracing  the  region  around  Sunset,  Maricopa  and 
the  Maricopa  flats.  Its  northern  limits  are  placed  at  the  furthest  town- 
ship north  of  the  San  Bernardino  Meridian  (T.  12  N.),  at  which  point 
the  Midway  district  is  considered  as  beginning.  The  oil  has  collected 
along  a  monocline  that  runs  from  Sunset  to  Maricopa,^nd  in  a  plunging 
syircTthe  which  lies  just  north  of  Maricopa,  and  finally  in  the  great 
"Thirty-five"  or  "iMaricopa"  anticline,  which  runs  out  of  the  hills  into 
Maricopa  flats  at  the  northern  end  of  the  field.  This  last  structure  has 
been  one  of  tlie  most  prolific  folds  discovered  in  California.  On  its 
northern  flank  is  located  well  No.  1  of  the  old  Lake  View  Oil  Company. 
This  well  w;is  probably  the  largest  ever  'brought  in'  in  California.  It 
flowed  wild  for  approximately  eighteen  months,  with  a  reported  produc- 
tion of  over  8,000,000  barrels  and  a  maximum  daily  production  of  about 
65,000  barrels.  At  the  present  time  it  is  producing  about  30  barrels 
per  day.  The  Sunset  field  may  be  considered  as  about  three-fourths 
drilled  up.  The  most  favorable  area  for  extension  lies  eastward  from 
Hazelton  and  Pentland  towards  the  San  Emigdio  District,  especially 
along  the  Pioneer  anticline  and  the  Western  INIinerals  area.  In  INIareh, 
1921,  the  total  proven  area  in  this  field  was  5868  acres. 

The  Midway  district  may  be  considered  as  comprising  the  region 
around  Taft,  Fello^vs,  Shale  and  the  Buena  Vista  Hills.  The  oil  has  col- 
lected along  three  general  lines  of  structure.  The  first  of  these  may  be 
considered  a.s  an  eastward-dipping  monocline,  containing  minor  anti- 
clinal folds,  some  of  which  are  quite  extensive,  such  as  the  "Twenty^-five 
Hill  anticline. "  This  structure  exists  along  the  foothills  of  the  Temblor 
Range,  west  of  the  IMidway  Valley,  and  in  general  takes  in  the  region 
back  of  Taft  and  Fellows.  The  Avells  on  this  structure  average  around 
2000  feet  in  depth  and  are  fair  and  constant  producers.  East  of  thi 
area  lies  the  IMidway  Valley,  which,  structurally,  is  a  plunging  syncline. 
While  oil  has  collected  along  this  structure,  the  wells  are  not  very  prolific 
and  this,  together  with  the  depth  to  the  oil  (average  about  3000  feet)  and 
serious  water  conditions,  has  not  made  drilling  very  profitable  in  this 
area.  The  last  structure  consists  of  the  dome  of  the  Buena  Vista  Hills, 
which  lies  .iust  east  of  the  ^Midway  Valley.  In  general  these  hills  may 
be  regarded  as  an  elongated  dome,  along  th(^  crest  of  which  there  are 
minor  anticlinal  folds.  This  region  is  the  district  of  the  largest  pro- 
ducers and  the  heavy  gas  pressure.  It  is  probable  that  the  IMcNee 
lease  of  the  Standard'Oil  Company,  on  Sec.  36.  T.  31  S..  R.  23  E.,  when 
in  its  prime  about  eight  years  ago,  was  the  most  prolific  square  mile  of 


•S 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  167 

oil  territory  in  the  world.  The  average  depths  of  wells  in  the  area  is 
about  3000  feet.  While  big  gushers  are  no  longer  found  here,  the  region 
still  produces  fair  sized  wells. 

In  general,  the  ^lidway  district  may  1)0  considered  as  two-thirds  drilled 
up.  The  most  favorabl(>  arca.s  for  exteusion  lie  at  the  cast  and  west  ends 
of  the  Buena  Vista  Hills.  In  addition  the  region  north  from  Fellows 
to  IMcKittrick,  lying  ea.st  of  the  highway,  offers  opportunity  for  small- 
well  development. 

In  ]\Iarch,  1921,  the  total  proven  area  was  39,447  acres.  The  total 
daily  average  production  in  the  Midway-Sunset  area  in  December,  1920, 
was  84,580  barrels  of  oil.  The  average  number  of  wells  producing  was 
2429,  with  an  average  daily  production  per  well  of  35  barrels  of  oil  and 
18  of  water.  The  gravity  ranges  from  al)out  11°  Baume  to  31°  Baume, 
the  heavy  oil  being  found  along  the  outcrops  in  the  Sunset  district,  while 
the  lighter  oil  is  encountered  in  the  sealed  anticlines  of  the  IMaricopa 
Flat  and  the  Buona  Vista  Hills.  Figure  2,  section  1,  page  17,  .shows 
the  general  structure  across  the  IMidway  field  in  the  vicinity  of  Taft. 

McKITTRICK    FIELD. 

The  ^IcKittrick  field  lies  about  three  miles  north  of  the  present 
nortlieni  limits  of  tlie  Midway  field.  It  is  probable,  however,  that  future 
drilling  in  the  low  hills  east  of  the  highway  will  connect  the  two  fields. 
These  low  hills  contain  several  well  developed  anticlines  in  the  iMcKit- 
trick  formation  which  are  capal)le  of  producing  small  wells  of  heavy 
oil  at  depths  of  from  1000  to  1500  feet. 

The  structure  of  the  McKittrick  field  as  mapped  by  Arnold  &  Johnson^ 
is  extremely  complicated,  consisting  of  a  double  anticline,  overturned. 
However,  recent  Avork  on  the  underground  structure  indicates  that  this 
is  not  the  condition.  A  peg  model,  based  on  the  well  logs  and  con- 
structed by  the  Department  of  Petroleum  and  Gas  of  the  State  ^Mining 
Bureau  at  Taft,  indicated  that  the  structure  really  consists  of  a  great 
over-thrust  fault,  the  older  I\Ionterey  shale  being  thrust  over  the  younger 
McKittrick  beds.  This  structural  condition  exists  in  the  McKittrick 
field  proper,  which  lies  between  iMcKittrick  and  Reward,  and  west  of 
the  McKittrick  Valley.  The  wells  start  down  in  the  diatomaceous  shale 
of  the  JMonterey  and  encountei-  showings  in  these  beds,  but  the  productive 
sands  are  not  reached  until  the  McKittrick  sands  are  entered  below 
the  fault  zone.  While  the  wells  are  not  large  producers,  they  are 
steady  and  long-lived,  and  show  a  remarkably  slow  rate  of  decline. 
This  probably  is  due  to  the  fact  that  the  oil  is  heavy  and  continues  to 
hold  the  gas  in  solution  over  a  long  period  of  time,  thus  forcing  it 
to  do  its  full  share  of  work  in  expelling  it  from  the  sands.  This 
process  is  explained  more  fully  in  Chapter  I,  under  "Saturation  and 
Recovery. ' ' 

The  low  hills  east  of  the  ^McKittrick  field  proper,  and  separated  from 
it  by  the  McKittrick  Valley,  which  structurally  is  a  syncline,  are  known 
as  the  McKittrick  Front  field.  The  structure  here  consists  of  three 
small,  parallel  anticlines.  Periodically  this  area  has  been  the  scene  of 
t^fiHing  operations,  which  after  a  few  years  have  ceased  and  the  wells 

'U.  S.  Geol  Survey.  Bull.  406.  Preliminary  Report  on  the  McKittrick-Sunset  Oil 
Region.      By  Ralph  Arnold  and  Harry  Johnson.   1909. 


168  CALIFORNIA  STATE  MINING  BURE.\U. 

for  the  most  part  have  been  abandoned.  At  the  present  time  the  produc- 
tive region  is  confined  to  the  property  of  the  Cymric  Oil  Company  and 
Nevada  County  Oil  Company.  There  is,  however,  no  reason  wlw  this 
area  should  not  be  commercially  productive,  as  past  drilling  and  the 
present  return  on  the  Cymric  and  Nevada  County  properties  indicate 
that  long-lived  wells  of  from  30  to  40  barrels  daily  yield  can  be  obtained 
at  depths  ranging  from  800  to  1500  feet.  The  gravity  of  the  oil  is  about 
15°  Baume.  The  trouble  with  the  past  work  has  been  that  the  chief 
company  which  formerly  operated  there  was  lax  in  shutting  off  water, 
and  was  mainly  concerned  with  drilling  deep  holes  into  the  IMonterey 
shale,  where  only  small  showings  were  encountered,  whereas  the  real 
production  lies  at  moderate  depths  in  the  jNIcKittrick  formation. 

In  March,  1921,  the  total  proven  area  in  the  McKittrick  field  was  1635 
acres.  The  total  daily  average  production  in  December,  1920,  was  7260 
barrels.  The  average  number  of  wells  producing  was  377,  with  an 
average  yield  per  well  per  day  of  20  barrels  of  oil  and  70  of  water. 

BELRIDGE    FIELD. 

The  Belridge  field  lies  out  in  the  flat  valley  area,  about  four  miles  north 
of  the  jMcKittrick  field.  The  structure  connsists  of  a  buried  anticlinal 
fold,  of  which  there  is  no  surface  evidence.  "Well  logs  indicate  that  the 
McKittrick  formation  is  present  on  the  axis  to  a  depth  of  about  800  feet, 
below  which  brown  shale  is  encountered,  this  probably  being  diatomaceous 
shale  of  the  Monterey  or  Santa  Margarita  formations.  There  are  two 
distinct  oil  zones,  one  a  shallow,  heavy  oil  zone,  found  at  the  base  of  the 
McKittrick  formation,  and  the  second  a  deep  light-oil  zone,  found  in  the 
Monterey  shale.  The  first  zone  is  the  principal  source  of  production 
and  yields  from  40  to  60  barrel  wells  of  from  17°  to  24°  Baume  gravity 
oil,  at  depths  ranging  from  800  to  1200  feet.  The  light-oil  zone  consists 
of  lenticular  areas  of  fine,  sandy  shale,  which  produces  a  light-gravity 
oil  of  over  30°,  commonly  known  as  shale  oil.  The  depths  of  wells  in 
this  zone  vary  from  3000  to  4500  feet,  and  generally  have  an  initial 
production  of  about  150  barrels.  The  zone,  however,  is  extremely 
spotted,  and  no  correlation  of  the  sands  from  well  to  well  is  possible. 
The  North  Belridge  field  lies  at  the  southern  end  of  the  Antelope  Hills, 
and  has  a  small  production  from  sandy  lenses  of  shale  in  the  IMonterey 
and  Santa  Margarita  formations. 

THE   LOST   HILLS   FIELD. 

The  Lost  Hills  field  lies  about  twelve  miles  north  of  Belridge.  The 
structure  consists  of  an  anticlinal  fold  striking  about  N.  45°  W.  and 
plunging  sharply  to  the  southeast.  The  only  surface  evidence  consists 
of  a  few  outcrops  at  the  northern  end,  and  it  has  been  necessar}'  to 
determine  the  positions  of  the  fold  by  well  logs,  as  in  the  case  of  the 
Belridge  field.  The  structure  is  probably  a  continuation  of  the  Kettle- 
man  Hills  anticline.  The  underground  conditions  are  similar  to  those 
of  the  Belridge  field.  The  wells,  however,  are  generally  larger  and  better 
producers  than  in  the  latter  area.  In  March.  1921,  the  total  proven 
area  in  the  Belridge-Lost  Hills  area  was  4379  acres.  The  total  daily 
average  production  in  December,  1920,  was  11,500  barrels.     The  average 


PETROLEUM    RESOURCES   OF    C^VLIFORNIA.  169 

number  of  wells  producing  was  571,  with  a  daily  average  yield  per  well 
of  21  barrels  of  oil  and  21.5  of  water. 

The  limits  of  both  the  Belridge  and  Lost  Hills  fields  have  been  prac- 


a  great  nat-toppea  aome  on  wnicn  the  dips  range  from  li"  to  lU".    On  ~ 


Elk  Hills  Field,  Kern  County  (Showing-  Tupman  Lease  of  Standan 


'""'"M  inri?" 


,S3i 


ing  Tupiiiaii  Ltuac  o!  Standard  Oil  Company,  Sec.  36,  T.  30  S.,  R.  24  E.), 


168  CALIFORNIA   STATE   MINING  BURE.\U. 

for  the  most  part  have  been  abandoned.  At  the  present  time  the  produc- 
tive region  is  confined  to  the  property  of  the  Cymric  Oil  Company  and 
Nevada  County  Oil  Companv.     There  is.  however,  no  reason  whv  this 


...jige 


PETROLEUM    RESOURCES   OP    CALIFORNIA.  169 

number  of  wells  producing  was  571,  with  a  daily  average  yield  per  well 
of  21  barrels  of  oil  and  21.5  of  water. 

The  limits  of  both  the  Belridge  and  Lost  Hills  fields  have  been  prac- 
tically determined.  Tliore  is.  however,  a  possibility  of  small-woU  devel- 
opments in  tlie  region  at  the  north  end  of  Lost  Hills  and  around  the 
North  Belridge  area. 

THE   DEVILS   DEN    FIELD. 

The  Devils  Den  field  lies  to  the  northwest  of  Lost  Hills.  While 
.small,  shallow  wells  of  from  five  to  ten  barrels  have  been  reported  in 
this  region  for  a  number  of  years,  no  commercial  production  has  been 
obtained  to  date.  These  wells  lie  in  the  flat  valley  area  to  the  south  and 
east  of  what  is  known  as  the  Pyi'finiid  Hills.  The  formations  exposed 
in  these  hills  consist  mainly  of  diatomaeeous  shale  of  the  Santa  jNLargarita, 
with  some  Vaqueros  sandstone.  Both  formations  are  folded  into  a 
number  of  sharp  antjclines.  In  the  region  to  the  west  of  the  hills,  the 
older  Cretaceous  and  Oligocene  formations  are  exposed.  On  the  eastern 
edge  of  the  hills  the  shale  dips  at  angles  of  from  30°  to  40°  to  the  east, 
and  apparently  disappears  beneath  the  valley  soil.  It  is  probable,  how- 
ever, that  beneath  the  valley  soil  the  IMcKittrick  formation  is  present, 
lying  uneonfonnably  against  the  shale,  and  dipi)ing  at  a  slightly  less 
angle  to  the  east.  The  oil,  which  probably  had  its  origin  in  the  shale, 
has  apparently'  collected  at  the  contact  of  these  two  formations,  mainly 
iirtlic  basal  sands  of  the  McKittrick.  If  the  surface  sand  could  be 
renioved.  it  would  probably  be  apparent  that  the  so-called  Devils  Den 
field  is  nothing  more  than  a  series  of  seepages  at  the  contact  of  the  Santa 
Margarita  and  IMcKittrick  formations.  The  shallow  w^ells  above  referred 
to  start  down  in  the  valley  soil,  and  at  depths  from  100  to  300  feet 
encounter  these  seepages  and  oil  sands,  penetrating  them  for  about  50 
feet.  There  are  in  the  neighborhood  something  like  twenty  of  these 
shallow  welLs,  almost  all  of  which  have  encountered  oil,  and  have  been 
reported  as  capable  of  producing  from  five  to  ten  barrels  per  day.  How- 
ever, none  of  these  have  been  pumped  over  any  length  of  time,  so  no 
estimate  can  be  made  as  to  their  commercial  value.  The  chief  interest 
the  Devils  Den  district  has,  however,  is  that  it  indicates  that  the  McKit- 
trick formation  is  oil-bearing  in  this  region,  and  that  in  the  flat  area 
from  three  to  four  miles  east  of  the  region  of  the  shallow  wells  there 
may  be  a  buried  structure  which  is  capable  of  producing  large  Avells. 
Therefore,  the  flat  area  between  Devils  Den  and  the  Lost  Hills  field  is 
worthy  of  being  thoroughly  investigated  for  evidences  of  buried 
structure. 

THE   ELK    HILLS  FIELD. 

The  Elk  Hills  field  lies  to  the  northeast  of  the  Midway  district,  being 
separated  from  the  Bnena  Yista  Hills  by  the  ^Midway  Valley.  At  date  of 
this  report,  this  region  is  the  chief  'gusher'  area  of  the  .state.  In  Decem- 
ber, 1920,  a  total  of  34  wells  were  producing  approximately  40,000  bar- 
rels of  oil  per  day,  an  average  of  about  1176  barrels  per  well  per  day.  The 
initial  production  varies  from  2000  to  6000  barrels  in  the  Tupman  area 
and  from  100  to  400  barrels  in  the  Hay  area.  The  structure  consists  of 
a  great  flat-topped  dome  on  which  the  dips  range  from  2°  to  10°.     On 


170  CALIFORNIA    STATE    MINING   BUREAU. 

the  flanks  of  this  general  structure,  however,  there  are  a  number  of  sharp 
minor  anticlines,  which  apparently  do  not  influence  underground  condi- 
tions. The  actual  underground  structure  probably  conforms  in  a  large 
measure  to  the  surface  topogra])hy.  To  date  the  proven  area  consists 
of  two  districts,  one  in  the  vicinity  of  Sec.  36,  T.  30,  R.  23  E.,  known  as 
the  Hay  area,  and  the  other  in  tlie  vicinity  of  Sec.  36,  T.  30,  R.  24  E., 
known  as  the  Tnpman  area.  Drillins:  to  date  indicates  that  the  proven 
area  can  be  carried  to  a  distance  of  about  one  mile  north  or  south  of  the 
center  of  the  dome.  The  total  proven  area  in  March,  1921,  was  1451 
acres.  Following  is  a  brief  description  of  the  field,  written  for  this  report 
by  C.  C.  Thorns  •} 

"The  Elk  Hills  cover,  roughly  speaking,  an  elliptical  area  about  six- 
teen miles  long  and  seven  miles  wide,  with  the  major  axis  running  in  a 
northwesterly  and  southeasterly  direction.  These  hills  reach  a  maximum 
elevation  of  about  1540  feet  in  Sec.  28.  T.  30  S.,  R.  23  E.,  M.  D.  B.  and  M., 
and  topographically  represent  the  anticlinal  structure  of  the  area. 

''The  structure  probably  represents  a  single  major  anticline  with 
minor  folds  on  either  flank  which  ])robably  do  not  extend  deep  enough 
to  affect  the  oil  l)earing  formation,  or  if  they  do  reach  that  depth  are 
mere  slight  undulations.  The  surface  drainage  indicates  that  the  present 
crest  of  the  hills  corresponds  quite  closely  with  the  axis  of  the  fold. 
This  broadly-arching  anticline  has  low  angles  of  dip  and  probably  extends 
from  about  IMcKittrick  to  the  north  end  of  Buena  Vista,  where  it  plunges 
beneath  the  San  Joaquin  Valley.  The  axis  of  the  fold  probably  passes 
south  of  the  northeast  corner  of  Sec.  8,  T.  31  S.,  R.  25  E.  Sufficient 
drilling  has  not  yet  been  done  to  definitely  locate  the  sub-surface  struc- 
ture. However,  present  indications  are  that  the  probable  axis  runs  from 
a  point  near  the  northeast  corner  of  Sec.  8,  T.  31  S.,  R.  25  E.,  about 
through  the  center  of  Sec.  6,  T.  31  S.,  R.  23  E.,  the  northwest  corner  of 
See.  1,  T.  31  S.,  R.  24  E.,  then  nearly  in  a  straight  line,  slightly  convex 
to  the  north,  to  about  the  northeast  corner  of  Sec.  36,  T.  30  S.,  R.  23  E. 

"The  approximate  dips  as  shown  by  the  correlations  of  the  oil-bearing 
formations  are  as  follows : 

"Dip  along  the  east  line  of  the  Standard  Oil  Company  Tupman  wells, 
on  Sec.  36,  T.  30  S.,  R.  24  E.,  abont  400'  in  a  mile  to  tlie  north. 

"Dip  along  the  south  line  of  the  Standard  Oil  Company  Tupman  wells 
is  about  500'  in  a  mile  to  the  east.  The  dip  to  the  southwest  from  the 
northeast  corner  of  Sec.  36,  T.  30  S.,  R.  23  E..  is  about  230'  to  the  mile. 

"The  logs  of  the  wells  on  Sec.  36.  T.  30  S.,  R.  24  E.,  and  Sec.  31,  T.  30 
S.,  R.  26  E.,  show  about  700'  of  sandy  formation  (sandy  shale  or  sand), 
then  about  2000'  of  shale  or  sandy  shale.  At  this  point  the  top  of  the 
oil  zone  is  encountered,  which  in  the  deepest  well  stratigraphically  in  this 
area  has  been  drilled  only  about  340'  below  the  top  of  the  oil-bearing 
formation.     These  oil-bearing  formations  are  mainly  sand. 

' '  The  logs  of  the  wells  of  the  Standard  Oil  Company  wells  on  the  Hay 
and  Carman  leases  on  Sec.  36,  T.  30  S..  R.  23  E.,  show  about  1200'  of 
sandy  shale  and  sand  above  the  gas  zone,  then  about  1200'  of  rotten  shale 
comprising  the  gas  zone.  From  this  depth  to  the  greatest  depth  drilled 
in  this  area  lies  the  oil  zone,  which  is  practically  all  sandy  shale.  The 
deepest  well,  stratigraphically,  in  this  westerly  portion  of  the  proven 

•Deputy  State  Oil  and  Gas  Supervisor,  Taft,  California. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  171 

field  is  Standard  Oil  Company  well  No.  15,  which  has  been  drilled  about 
1400'  below  the  top  of  the  oil  zone. 

"There  is  not  sufficient  i:-('olo<,M<'al  information  available  to  correlate 
stratigraphically  the  formation  in  the  easterly  and  westerly  portions  of 
the  proven  Elk  Hills  field,  and,  therefore,  it  cannot  be  said  definitely 
whether  or  not  the  oil-bearing  zones  in  the  two  fields  are  at  the  same 
stratigraphic  horizon.  The  upper  or  sandy  formations,  however,  are 
probably  Tulare  or  Paso  Kobles.  The  formations  below  this  depth  are 
probably  all  Etchegoin,  since  it  is  the  generally  accepted  belief  that  none 
of  the  wells  in  this  field  have  yet  been  drilled  deep  enough  to  reach  the 
Montere}'.  The  oil-bearing  formations  in  the  easterly  portion  of  the  field, 
it  will  be  noted,  are  mainly  sand,  while  those  of  the  westerly  portion 
are  shale  or  sand}-  shale. 

"No  prominent  markers  have  yet  been  noted  in  this  field  above  the 
oil  zone.  Occasionally  some  two  or  three  wells  seem  to  show  a  possible 
marker  above  tbe  oil  zone,  but  adjacent  wells  lack  such  markers.  The 
main  oil  sand,  however,  does  seem  to  be  a  consistent  marker  in  the 
eastern  portion  of  the  field. 

"No  ])romin('nt  water  zones  luivc  been  noted  and  no  water  has  been 
found  below  the  top  of  the  oil  zone  in  the  easterly  portion  of  the  field 
or  below  the  top  of  the  gas  zone  in  the  westerly  portion  of  the  field. 
The  lowest  top  water  has  been  quite  definitely  located  as  being  about 
200  feet  above  the  top  oil  sand. 

"As  has  been  noted  above,  in  the  westerly  portion  of  the  field  there 
is  a  1200'  gas  zone,  while  in  the  easterly  portion  no  gas  zone  has  been 
noted.  See.  36.  T.  30  S.,  R.  24  E.,  M.  D.  B.  and  M.  Only  one  oil 
zone  has  apparently  been  penetrated  and  the  depth  and  thickness  of 
this  zone  has  not  been  determined,  since  the  deepest  wells  drilled  are 
apparently  still  within  the  zone." 

For  a  complete  description  of  the  "West  Side  fields  the  reader  is  referred 
to  the  publications  of  the  T7uited  States  Geological  Survey'^  and  the  Cali- 
fornia State  ]\lining  Bureau. - 

A  full  description  of  the  surface  geology  and  underground  conditions 
will  be  found  in  these  reports.  In  addition,  peg  models  of  the  various 
fields  are  open  to  inspection  at  the  office  of  the  Department  of  Petroleum 
and  Gas,  California  State  ^Mining  Bureau,  Taft,  California. 

COALINGA   FIELD. 

This  is  the  most  northerly  field  in  California  from  which  any  appre- 
ciable amount  of  production  is  being  obtained.  Tin  re  lypcs  of  structure 
are  present.  '  'The  great,  plunging  Coalinga  anticline,  wliidi  I'uns  out 
into  the  valley  in  a  southeast  direction,  forms  what  is  known  as  the  'East 
Side  field,'  and  furnishes  the  greater  portion  of  the  production.  Lying 
west  of  this  anticline  is  the  plunging  Coalinga  syncline,  which  runs 
down  the  Pleasant  Valley.  "An  area  around  the  head  of  this  syncline 
is  productive^  SjOn  the  west  side  of  the  Pleasant  Valley,  and  forming  the 

'U.  S.  Geol.  Survey.  Bull.  406.  Preliminarv  Report  on  the  McKittrirk-Sunset  Oil 
Region.  By  Ralph  .\rnolcl  and  Hanv  .John.son.  1909.  U.  S.  Geol.  Survey.  Professional 
Paper  116.      The  Sun.'^et-Midway  Oil  Field.      By  R.  W.  Pack,  1920. 

-'California  State  Mining  Bureau.  Bull.  69  and  Map  folio.  Petroleum  Industry  of 
California.  By  R.  P.  McLaughlin  and  C.  A.  Waring,  1914.  First,  Second,  Third,  Fourth 
and  Fifth  .Annual  Reports  of  the  State  Oil  and  Gas  Supervisor,  California  State  Mining 
Bureau. 


172  CALIFORNIA    STATE    MINING   BUREAU. 

west  limb  of  the  Coalinga  syncline,  is  the  'West  Side'  field.     This 
structure  is  a  monocline. 

The  formations  exposed  along  this  monocline  and  on  the  Coalinga 
anticline  consist  of  the  Cretaceous,  the  Tejon,  the  Kreyenhagen  shales, 
the  Vaqueros  sandstone,  the  Santa  ]\Iargarita  and  the  Etchegoin  and 
Jacalitos  formations.  These  last  three  formations  are  not  oil-bearing 
in  this  region,  and  only  act  as  an  overburden  above  the  oil  measure. 

The  greater  portion  of  the  oil  was  formed  by  the  Kreyenhagen  shales 
and  has  collected  in  the  sandstone  beds  of  the  Vaqueros  formation.  This 
oil  is  black  and  of  an  asphaltic  base.  The  gravity  ranges  from  about 
11°  to  38°  Baume. 

A  little  oil  was  also  formed  by  the  Moreno  shale,  which  is  the  upper- 
most member  of  the  Chico.  This  oil  is  found  in  the  old  Oil  City  field, 
at  the  head  of  the  Coalinga  anticline.  This  is  the  only  region  in  Cali- 
fornia where  the  Cretaceous  is  commercially  productive.  Here,  under 
the  most  favorable  conditions,  the  total  daily  production  is  135  barrels. 
This  comes  from  twelve  producing  wells.  The  oil  is  light  green  in  color 
and  ranges  above  50°  in  gravity. 

The  wells  in  the  West  Side  field  range  from  500  to  2500  feet  in  depth. 
Those  at  the  head  of  the  syncline  and  along  the  Coalinga  anticline  in 
the  East  Side  field  range  from  800  to  4000  feet  in  depth.  In  March, 
1921,  the  total  proven  area  was  14,272  acres.  The  total  daily  average 
production  in  December,  1920,  was  40,500  barrels  of  oil.  The  average 
number  of  wells  producing  was  1288,  with  an  average  daily  yield  per 
well  of  35  barrels  of  oil  and  10  of  water. 

The  limits  of  the  field  are  practically  fixed,  with  the  possible  exception 
that  the  proven  region  may  be  extended  south  of  Waltham  Canyon  along 
the  Jacalitos  anticline  Old  wells  drilled  in  this  region  have  reported 
small  showings,  and  it  is  worthy  of  being  examined  carefully  as  a  pos- 
sible productive  area.  The  region  west  of  the  proven  area  and 
up  Waltham  Canyon,  west  of  Alcade,  is  not  favorable  for  drilling 
operations. 

For  a  detailed  description  of  the  geology  and  underground  conditions, 
the  reader  is  referred  to  the  publications  of  the  United  States  Geological 
Survey^  and  the  State  Mining  Bureau. - 

KERN    RIVER   FIELD. 

This  field  lies  along  the  Kern  River,  just  north  of  the  town  of  Bakers- 
field.  The  structure  consists  of  a  low  monocline,  dipping  to  the  south- 
west, the  dips  varying  from  5°  to  7°.  The  reason  for  the  oil  collecting 
in  a  structure  such  as  this  is  somewhat  obscure.  Following  are  two 
theories  Avhich  may  possibly  account  for  the  accumulation:  the  first  is 
that  the  oil  has  been  trapped  in  the  monocline  by  a  buried  anticlinal  fold 
which  lies  out  in  the  valley  west  of  Bakersfield.  The  second  is  that  the 
oil  has  accumulated  by  reason  of  the  unconformity  of  the  McKittrick 
beds  on  the  upturned  edges  of  the  IMonterey  shale.     The  oil  is  found 

'U.  S.  Geol.  Survey.  Bull.  39S.  The  Geology  and  Oil  Resources  of  the  Coaliiga 
District.  By  Ralph  Arnold  and  Robert  Anderson,  1910.  U.  S.  Geol.  Survey.  Bull. 
581-D.  Geology  and  Oil  Prospects  of  the  Waltham.  Priest,  Bitterwater  and  Peachtree 
Valleys.     By  R.  "W.   Pack  and  W'alter  English,   1914. 

^California  State  Mining  Bureau.  Bull.  69.  Petroleum  Industry  of  California.  Bv 
R.  P.  McLaughlin  and  C.  A.  Waring.  The  First,  Second,  Third,  Fourth  and  Fiftii 
Annual  Reports  of  the  State  Oil  and  Gas  Supervisor,  California  State  Mining  Bureau. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  173 

in  the  loose,  incoherent  sands  of  the  upper  portion  of  the  IMcKittrick 
formation,  and  probably  had  its  oriirin  in  the  diatomaceous  shale  of  the 
Monterey  Along  the  northeast  edge  of  the  fieUl  the  bitnininized  beds 
at  the  base  of  the  ^IcKittriek  may  be  seen.  However,  no  jNIonterey 
shale  is  exposed,  the  IMcKittrick  beds  aparently  overlapping  directly  on 
the  Vaqueros  formation  which  in  turn  rests  on  the  granite.  At  Poso 
Creek,  however,  the  jMonterey  shale  is  exposed  beneath  the  IMcKittrick 
and  it  is  probably  present  beneath  these  latter  beds  over  a  considerable 
portion  of  the  Kern  River  field. 

Tliis  field  is  a  consistent,  steady  producer  of  long-lived  wells  of  from 
40  to  100  barrels  daily.  The  oil  averages  in  gravity  about  15°  Baurae 
and  the  wells  range  in  depth  from  200  to  1500  feet.  The  total  proven 
area  in  March,  1921,  was  7152  acres.  The  total  daily  average  production 
in  December,  1020.  was  20.067  barrels  of  oil.  The  average  number  of 
producing  wells  was  2067  and  the  daily  average  yield  per  well  was  10 
barrels  of  oil  and  40  of  water. 

Recent  exploration  work  has  extended  the  field  north  to  Poso  Creek. 
The  wells  in  this  new  district  are  small  producers,  coming  in  with  an 
initial  yield  of  about  40  barrels  at  depths  of  about  2000  feet.  From  this 
it  is  apparent  tliat  the  Poso  Creek  district  is  not  going  to  be  as  prolific 
a  producer  as  the  old  field.  To  date,  no  commercial  production  has  been 
obtained  north  of  Poso  Creek,  but  several  wells  drilling  just  north  of  the 
creek  have  reported  showings,  and  it  is  probable  that  the  Poso  Creek 
district  can  be  extended  to  the  nortli  for  several  miles  j'et.  The  struc- 
ture and  geological  conditions  are  somewhat  obscure,  as  there  is  a  lack 
of  good  surface  outcrops.  It  is  proliable,  however,  that  the  same  condi- 
tions are  present  here  as  in  the  main  Kern  River  field. 

In  the  region  east  of  Bakersfield,  and  south  of  the  Kern  River,  no 
production  has  been  obtained  except  for  a  few  small  wells  along  the 
south  bank  of  the  river.  From  the  meager  surface  indications  that 
are  available,  it  is  probable  that  the  formations  which  are  present  in 
the  Kern  River  field  continue  south  across  the  river  and  underlie 
the  plateau  region  east  of  Bakersfield.  This  region  is,  therefore, 
worthy  of  being  examined  carefully  as  a  possible,  productive  area. 

UNPROVEN  AREAS. 
SOUTH    END  OF  THE  VALLEY. 

Tliis  i-egion  includes  the  tiat  i)ortion  of  the  valley  lying  south  of 
Tulare  Lake,  together  with  the  foothills  of  the  San  Emigdio  and 
Tejon  regions. 

This  foothill  area  at  the  south  end  of  the  valley  has  been  mapped 
and  reported  on  by  the  U.  S.  Geological  Survey.^ 

The  formations  exposed  along  the  San  Emigdio  and  Tejon  hills  are 
similar  to  those  found  in  the  IMidway-Sunset  district.  At  IMuddy 
Creek  and  along  "Wheeler  Ridge  there  are  seepages  of  oil  in  the  McKit- 
trick  formation.  The  general  structure  of  this  foothill  area,  how- 
ever, is  unfavorable  for  the  accumulation  of  petroleum,  with  two 
exceptions:  these  consist  of  the  Wheeler  Ridge  anticline  and  the  Tejon 

'U.  S.  Geol.  Survey.  BuU.  741.  Preliminary  Report  on  the  Geology  and  Possible  Oil 
Resources  of  tlie  South  End  of  the  San  Joaquin  Valley.  By  Robert  Anderson,  1910. 
U.  S.  Geol.  Survey.  Professional  Paper  116.  The  Sunset-Midway  Oil  Field.  By  R.  W. 
Pack,  1920. 


174  CALIFORNIA    STATE   MINING   BURE/VU. 

Hills  autirline.  Both  of  the  striu-tiires  are  worthy  of  being  tested, 
and  the  Wheeler  Ridge  fold  is  now  being  drilled  on  by  the  Standard 
Oil  Company. 

In  the  flat  valley  area  lying  out  in  front  of  these  hills  and  extending 
north  to  Tulare  Lake,  there  are  no  surface  indications  of  petroleum. 
However,  the  outcrops  in  the  foothills  that  surround  this  portion  of 
the  valley  on  three  sides  indicate  that  it  is  underlaid  by  the  ^Miocene 
diatomaceous  shale,  and  the  reservoir  beds  of  the  ]\IcKittrick  forma- 
tion and,  as  stated  in  the  article  on  "Buried  Structures,"  it  may 
possibly  contain  anticlines  which  may  prove  i)roductive.  Section  C-D, 
(page  165)  is  a  hypothetical  section  across  this  portion  of  the  valley,  and 
shows  how  possible  oil-bearing  structures  may  exist. 

REGION  OF  THE  FOOTHILLS  OF  THE  TEMBLOR   RANGE. 

This  area  lies  west  of  the  Sunset-Midway,  jNIcKittrick  and  Lost  Hills 
fields.  In  general  this  region  is  not  favorable  for  tlie  accumulation 
of  any  appreciable  amount  of  petroleum.  The  formations  are  older 
than  those  of  the  producing  field,  and  the  structure  is  highly  tilted 
and  folded.  On  Sec.  36,  T.  29  S.,  R.  20  E.,  there  is  a  production  of 
about  20  barrels  per  day  of  15°  Baume  gravity  oil,  from  about  fifteen 
shallow  wells.  This  is  known  as  the  Temblor  field.  The  oil  has 
accumulated  in  the  Vacjueros  sandstone  at  a  point  where  it  is  faulted 
against  the  ^Monterey  shale.  The  accumulation  is  only  local  and  of  no 
great  conuuercial  value.  In  the  Gould  Hills  there  are  some  tar  sands 
at  the  contact  of  the  Santa  ^Margarita  and  ]\IcKittrick  formations. 
Wells  drilled  here  have  encountered  small  showings  of  heavy  oil,  and 
there  is  no  reason  to  believe  that  future  drilling  would  meet  with  any 
better  success.  In  the  flat  area  lying  between  the  northern  end  of 
the  Temblor  Range  and  the  Lost  Hills-Belridge  area,  there  is  a 
possibility  that  buried  anticlinal  folds  exist  which  may  be  productive 
later.  This  region  is  known  as  the  Antelope  Hills  and  Antelope  Plain 
district. 

KETTLEMAN    HILLS. 

The  district  consists  of  the  range  of  hills  running  from  Coalinga 
south  to  Lost  Hills,  and  lying  just  west  of  Tulare  Lake.  They  are 
separated  from  the  Diablo  Range  by  the  Kettleman  plain.  The  struc- 
ture of  these  hills  consists  of  a  great  anticline,  the  axis  of  which  runs 
along  the  highest  ridge  in  the  center  of  hills,  with  a  general  northwest 
and  southeast  trend.  The  dips  on  the  flank  vary  from  10°  to  35°. 
This  structure  may  be  considered  as  a  continuation  of  the  Coalinga 
anticline  and  it,  in  turn,  continues  into  the  Lost  Hills  region.  The 
formations  exposed  along  the  axis  of  this  fold  are  soft,  loose  sands 
and  clays  of  the  Etchegoin  formation.  As  to  what  is  present  beneath 
these  beds  there  is  no  direct  evidence.  It  can  be  assumed,  however, 
that  in  the  northern  portion,  formations  similar  to  those  found  in  the 
Coalinga  field  should  be  present;  while  on  the  southern  end,  rocks 
similar  to  those  found  in  the  Lost  Hills  and  Devils  Den  district  should 
be  present.  This  assumption  is  based  not  only  on  the  fact  that  the 
Kettleman  Hills  is  a  portion  of  the  general  structure  that  runs 
from    Coalinga   to   Lost   Hills,    and   should,    therefore,    contain   rocks 


PETROLEUM    RESOURCES   OF    CALIFORNIA. 


175 


0  those  regions,  l)ut  it  is  also  based  on  a  study  of  the  forma- 
osed  in  the  hills  west  of  the  Kottlenian  plain  and  which  runs 


■By  IWi^-ii  j^iiiuiu  aim  rcooert  Anaerson,  I9i( 


Midway  Oil  Field,  Kern  County  (Looking  East  from  Fellows 


East  from  Felbws;  Elk  ffiUs  and  Buena  Vista  in  Backgfround) . 


174  CALIFORNIA    STATE   MINING   BUREiVU. 

Hills  anticline.     Both   of  the  struetures  arc  -worthy  of  being  tested, 
and  the  Wheeler  Ridge  fold  is  now  being  drilled  on  by  the  Standard 


from    Coalinga   to    Lost   Hills,    and    should,    therefore,    contain   rocks 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  175 

similar  to  those  regions,  but  it  is  also  l)asetl  on  a  study  of  tlie  forma- 
tions exposed  in  the  liills  west  of  the  Kettleman  ])lain  and  which  runs 
from  Waltham  Canyon  to  Devils  Den. 

The  oil  possibilities  may  be  summed  up  as  follows:  The  structure 
is  extremely  favorable  for  the  accuiuulalion  of  petroleum.  At  the 
northern  end  of  the  hills  it  is  possible  tbat  the  oil-bearing  formations 
similar  to  those  found  in  the  Coalinsa  field  may  be  present,  while 
in  the  southern  end  a  similar  condition  may  exist  in  regard  to  the  oil- 
bearing  fornuitions  of  the  Lost  Hills  region.  Wliether  or  not  these 
formations,  if  present,  would  contain  oil  in  commercial  ciuantities, 
or  be  within  reach  of  the  drill,  can  only  be  told  by  actual  drilling. 
Wells  drilled  to  date  indicate  that  there  is  no  commercial  production 
above  approximately  4000  feet.  There  are,  however,  sufificient  favor- 
able conditions  present  to  make  this  region  worthy  of  being  tested  by 
at  least  several  deep  wells  located  on  the  axis  of  the  fold. 

In  the  northern  end  about  nine  wells  have  been  drilled,  only  two 
of  which  were  located  sufficiently  close  to  the  axis  of  the  fold  to  afford 
a  fair  test.  These  two  wells  were  the  Coalinga-Kettleman,  located  in 
Sec.  4,  T.  22  S.,  R.  17  E,  and  drilled  to  a  depth  of  4810  feet,  and  the 
Medallion  Oil  Company  well,  located  in  Sec.  20,  T.  22  S.,  R.  18  E., 
drilled  to  a  depth  of  3848  feet.  Neither  of  these  wells  revealed  any 
showings  of  oil,  and  it  is  pi"obal)le  that  they  did  not  penetrate  deep 
enough  to  encounter  the  Vaciueros  sandstone  which  is  believed  to 
contain  the  oil  in  this  portion  of  the  hills. 

At  the  south  end  of  the  hills  two  wells  have  been  drilled  in  recent 
years,  one  of  which,  the  Crescent  Petroleum  Company's  well,  has  been 
abandoned,  and  second,  the  Standai'd  Oil  Company's  'Kettleman 
well,'  is  still  drilling.  The  Crescent  well  was  located  in  Sec.  2,  T. 
25  S.,  R.  19  E.,  and  was  drilled  to  a  depth  of  about  2700  feet.  Between 
1600  and  1700  feet  several  small  showings  of  black  oil  were  encountered. 
When  tested,  these  showings  yielded  al)out  3  bailers  full  of  oil.  It  is 
reported  that  the  Standard  Oil  Company,  in  their  well  on  Sec.  34, 
T.  24  S.,  R.  19  E.,  encountered  similar  showings  at  about  the  same 
depth.  The  foi'mations  penetrated  by  the  Crescent  well  were  soft 
sands  and  clays  of  the  iMcKittrick  series. 

A  description  of  the  geology  of  the  Kettleman  Hills,  as  well  as  the 
region  to  the  west,  can  be  found  in  Arnold  and  Anderson's  Coalinga 
report.^ 

KREYENHAGEN    HILLS    REGION. 

This  district  may  be  considered  as  comprising  the  foothills  of  the 
Diablo  Range,  between  Waltham  Creek  and  Devils  Den.  The  north- 
ern and  central  portions  are  known  as  the  Kreyenhagen  Hills  and 
the  southern  end  in  the  vicinity  of  the  McClure  Valley  is  known  as 
the  Pyramid  Hills.  The  general  structure  of  the  region  is  that  of 
a  steep  monocline  dipping  about  40°  to  the  east.  The  formations 
exposed  are  the  Cretaceous,  the  Eocene,  the  Kreyenhagen  shales,  the 
Vaqueros,  the  Santa  ]\Iargarita,  and  the  Etchegoin  and  Jacalitos 
formations.     At  the  northern  end,  in   the  vicinity  of  Waltham  and 

^U.  S.  Geol.  Survey.  Bull.  39S.  Geology  and  Oil  Resources  of  the  Coalinga  District. 
By  Ralph  Arnold  and  Robert  Anderson,  1910. 


176  CALIFORNIA    STATE   MINING   BUREAU. 

Jacalitos  creeks,  the  hills  widen  out  and  there  is  a  well-developed 
anticline  lying  in  the  hills  east  of  the  general  monoelinal  structure. 
This  fold  is  known  as  the  Jacalitos  anticline,  and  was  referred  to  in 
the  article  on  the  Coalinga  field  as  a  possible  productive  area.  The 
axis  of  this  fold  is  plunging  sharply  to  the  south,  so  tliat  in  the  vicinity 
of  Jacalitos  Creek  the  oil-bearing  formations  (Vaqueros)  are  more 
than  likely  below  a  depth  of  4500  feet.  The  Azores  well,  located  on 
the  axis  o'f  the  fold,  in  Sec.  26,  T.  21  S.,  R.  15  E.,  reached  a  depth 
of  4420  feet  and  found  only  slight  showings,  these  being  reported  at 
about  3500  feet.  At  the  northern  end  of  this  fold,  however,  in  the 
vicinity  of  Waltham  Canyon,  the  oil-bearing  formations  should  be 
shallower,  and  it  is  possible  that  the  proven  area  of  the  Coalinga  field 
may  be  extended  into  the  region.  Along  the  general  monoelinal  struc- 
ture of  the  central  and  southern  portions  of  this  region,  there  is  little 
possibility  of  obtaining  oil  in  any  appreciable  quantities.  This  is  due 
to  the  unfavorable  structure.  In  Canoas,  Big  Tar  and  Little  Tar 
canyons,  there  are  prominent  seepages  of  oil  in  the  basal  sands  of  the 
Vacpieros,  and  w^ells  drilled  here  have  encountered  small  quantities  of 
oil.  The  territory  in  the  region  of  these  canyons  is  known  as  the  Krey- 
enhagen  field.  Two  general  groups  of  wells  have  been  drilled  here; 
namely,  those  that  are  drilled  in  the  Kreyenhagen  shales  and  draw 
their  oil  from  sandy  beds  in  that  formation,  and  those  that  start  down 
in  the  Santa  INIargarita  and  probably  draw  their  oil  from  the  Vaqueros. 
The  first  group  is  credited  with  eight  wells,  all  of  which  encountered 
showings  and  one  of  which,  Kreyenhagen  No.  1,  located  in  the  SE^  of 
Sec.  32,  T.  22  S.,  R.  16  E.,  is  reported  to  have  yielded  at  the  rate  of 
about  15  barrels  per  day  at  the  start,  but  soon  fell  to  5  or  6  barrels. 
The  depth  of  the  well  Mas  650  feet.  The  oil  is  said  to  have  been  light 
green,  and  of  37°  Baume  gravity.  The  second  group  includes  four 
Avells,  all  of  which  encountered  showings  of  heav}',  black  oil.  Well 
No.  1,  of  the  Black  Mountain  Oil  Company,  located  in  the  NW:|^  of 
Sec.  33,  T.  22  S.,  R.  16  E.,  is  said  to  have  produced  5  or  6  barrels  of 
18°  Baume  gravity  oil  at  a  depth  of  720  feet.  None  of  the  wells  in 
either  group  were  of  commercial  value. 

This  region  is  chiefly  of  interest  because  the  oil-bearing  formations 
are  dipping  to  the  east,  and  may  possibly  continue  across  the  Kettle- 
man  plain,  and  come  up  again  in  the  Kettleman  Hills.  Here,  on 
account  of  the  anticlinal  structure,  the  conditions  for  the  accumula- 
tion of  oil  in  appreciable  quantities  would  be  quite  favorable.  In  the 
region  between  the  Kettleman  Hills  and  the  Kreyenhagen  Hills  there 
is  little  possibilit.v  of  finding  oil,  as  the  structure  is  tJiat  of  a  great 
syncline  in  which  the  oil-bearing  formations  are  beyond  the  reach  of 
the  drill,  and  also  very  likely  barren  of  oil.  The  geology  and  oil 
possibility  of  the  Kreyenhagen  Hills  is  covered  in  Arnold  and  Ander- 
son's Coalinga  Report.^ 

THE  REGION  NORTH  OF  COALINGA. 

This  district  includes  the  foothills  and  the  western  side  of  the 
valley  from  Coalinga  to  Livermore  Pass.  The  general  structure  of 
the  foothill  area  is  that  of  a  great  monocline  dipping  to  the  east.     In 

•U.   S.   Geol.   Survey.     Bull.   398.     The  Geology  and   Oil   Resources  of  the   Coalinga 
District.     By  Ralph  Arnold  and  Robert  Anderson,  1910. 


PETROLEUM    RESOURCES   OF    CALIFORNIA.  177 

the  hills  just  north  of  Salado  Creek,  and  at  the  mouth  of  Panoche 
Creek,  there  is  evidence  of  anticlinal  folds,  and  further  work  in  this 
region  may  disclose  other  folds.  The  formations  that  outcrop  along 
the  monocline  consist  of  the  Cretaceous,  the  P]occne,  the  Kreyenhageu 
diatomaeeous  shales,  sandstone  and  shale  beds  of  the  [Monterey  series, 
the  Santa  ^Margarita  formation,  and  finally  loose  sands,  clays  and 
shales  of  Pliocene  age,  belonging  to  the  Etchegoin,  Jacalitos  and  Tulare 
formations.  Of  these,  tlie  Krcyenhagcn  shales  and  the  sandstone  beds 
of  the  Monterey  series,  are  of  chief  interest,  as  the  former  is  a  probable 
source  of  petroleum,  and  the  latter  would  act  as  the  reservoir  forma- 
tion for  such  oil. 

The  popular  belief  that  there  are  no  evidences  of  petroleum  in  this 
region  is  contrary  to  facts.  Numerous  seepages  have  been  reported  to 
the  writer  a.s  occurring  along  ^Monocline  ridge.  In  the  SW  ^  of  Sec.  9, 
T.  16  S.,  R.  13  E.,  about  one-fourth  of  a  mile  southwest  of  the  Union 
Oil  Company's  well,  tliere  is  a  good  outcrop  of  dry  oil  .sand  which, 
when  tested  by  the  writer  with  ether,  gave  an  excellent  test  for 
petroleum.  'J'his  sand  occurs  about  the  middle  of  the  Monterey  series, 
and  would  indicate  Uiat  this  fornuition  is  a  possible  reservoir  for  oil 
in  this  region. 

The  possibilities  may  be  summed  up  as  follows :  Along  the  foothills 
the  chances  are  not  good  on  account  of  the  steep  monoclinal  structure. 
The  fact,  however,  that  the  Kreyenhagen  shales  outcrop  here,  and  are 
a  possible  source  of  oil,  and  that  the  lower  Pliocene  sands  above  them 
show  petroleum,  would  lead  to  the  ])elief  that,  if  favorable  structure 
could  be  found  in  this  region,  in  whjch  the  lower  ^Miocene  sands  were 
folded,  they  would  contain  petroleum  in  commercial  quantities.  The 
most  likely  place  for  such  structures  would  be  out  in  the  flat  valley 
area  lying  from  2  to  10  miles  east  of  the  foothills.  In  this  region 
it  is  possible  that  buried  anticlinal  folds  may  exist  similar  to  the  Lost 
HilLs  and  Belridge  areas,  and  along  the  axis  of  which  the  lower 
[Miocene  sands  would  be  present.  Consideration,  however,  must  be 
taken  of  the  fact  that  a  great  overl)urden  of  Pliocene  and  upper  [Mio- 
cene beds  are  also  present,  and  in  case  any  buried  fold  was  located, 
these  beds  would  have  to  be  penetrated  before  the  possible  oil  sands  of 
the  lower  Miocene  would  be  encountered.  However,  the  entire  region 
of  the  west  side  of  the  valley  may  he  considered  as  worthy  of  being 
carefully  examined  for  the  possibility  of  containing  buried  structure 
which  might  be  indicated  on  the  surface  by  low  mounds  or  ridges. 
Section  A-B,  Fig.  12  (page  165),  is  a  hypothetical  section  across  this 
portion  of  the  valley,  showing  how  {)ossible  oil-beai-ing  structures  may 
exist.  This  mattei-  is  also  taken  up  at  the  beginning  of  this  chapter 
under  "Buried  Structures." 

REGION    AROUND    TULARE    LAKE. 

In  the  low  marshy  area  around  Tulare  Lake  gas  has  been  obtained 
for  a  number  of  years  from  shallow  water  wells,  and  recently  some 
deep  wells  have  been  drilled  which  showed  large  Ciuantities  of  gas  at 
depths  below  2000  feet.  In  no  case,  however,  has  the  State  Mining 
Bureau  been  able  to  verify  any  of  the  reported  oil  -showings.  The  gas 
encountered  resembles  strongly  the  'marsh  gas'  obtained  in  the  wells 

12—13322 


178  C/VLIFORNIA    STATE   MINING   BUREAU. 

around  Stockton  and  Sacramento.  It  is  perfectly  odorless  and  burns 
with  an  uncolored  tlarae.  As  yet  there  is  no  evidence  that  this  gas  is 
connected  with  any  petroleum  deposit.  The  surface  in  this  region  is 
flat  and  covered  with  valley  alluvium  and  soil  wliich  gives  no  evidence 
as  to  what  is  beneath  it.  This  portion  of  the  valley,  however,  falls 
within  the  area  that  may  possibly  contain  buried  anticlinal  folds,  and 
it  is  possible  that  the  gas  found  here  has  accumulated  by  reason  of 
such  a  fold.  Whether  or  not  it  would  contain  petroleum,  or  actually 
exists,  can  only  be  told  by  drilling. 

BUTTON   WILLOW   DISTRICT. 

This  district  lies  about  8  miles  northeast  from,  and  parallel  to,  the 
Elk  Hills  field.  Running  in  a  northwest  direction  across  the  center 
of  T.  29  S.,  R.  24  E.,  is  a  low  ridge  which  continues  to  the  northwest 
in  the  direction  of  Lost  Hills.  It  is  believed  that  this  ridge  may  mark 
the  axis  of  a  buried  anticline  which,  on  account  of  its  relationship  to 
the  Elk  Hills  and  Lost  Hills  area,  should  be  highly  productive.  Out- 
side of  the  low  ridge  there  is  no  other  surface  evidence  that  would  indi- 
cate a  fold.  Attention  was  first  called  to  this  area  by  Mr.  R.  N. 
Ferguson,  of  Bakersfield,  who  gave  the  name  of  Button  Willow  anti- 
cline to  this  low  ridge.  At  the  present  time  four  wells  are  drilling 
here  and  encouraging  results  have  been  obtained  to  date.  The 
Petroleum  :\Iidway  wells,  located  in  Sec.  12,  T.  29  S.,  R.  23  E.,  and 
Sec.  6,  T.  29  S.,  R.  24  E.,  have  both  encountered  large  quantities  of 
gas  which  is  in  apparently  sufficient  amount  to  be  of  commercial  value. 
In  the  National  Exploration  well,  on  Sec.  27,  T.  28  S.,  R.  23  E., 
samples  tested  by  the  State  IMining  Bureau,  from  a  vicinity  of  3000 
feet,  gave  good  indications  of  petroleum.  The  region  may,  therefore, 
be  considered  as  Avorthy  of  being  thoroughly  tested.  It  may  also  be 
noted  here  that  the  results  obtained  at  Button  Willow  will,  in  a  large 
measure,  prove  or  disprove  of  the  theory  that  the  San  Joaquin  Valley 
contains  buried  productive  structures  other  than  those  already  known. 

EAST  SIDE  OF  THE  VALLEY. 

This  region  as  described  here  includes  the  eastern  portion  of  the 
valley  lying  north  from  the  vicinit}'  of  Tulare  Lake  to  Stockton.  The 
eastern  side  of  the  valley  lying  south  of  Tulare  Lake  has  been  included 
in  the  article  on  the  "South  End  of  the  Valley." 

At  Terra  Bella  the  Pliocene  beds  which  continue  on  north  to  this 
point  from  the  Kern  River  area,  disappear,  and  from  this  point  north 
to  the  region  east  of  ^ladera,  the  vallej'  soil  rests  directly  against  the 
crystalline  rocks  of  the  Sierra  Nevada.  Evidence  of  the  presence  of 
sedimentary  rocks  is  lacking,  and  it  is  probable  that  the  granite  is 
present  at  shallow  depths  beneath  the  surface  sand  over  a  great  portion 
of  this  region. 

From  the  vicinity  of  Madera  northward  to  Stockton,  the  foothills 
of  the  Sierra  Nevada  are  composed  of  highly-altered  slates  and  intru- 
sive rocks  belonging  to  the  ^lariposa  formation  (Jurassic).  Resting 
against  these  older  rocks  along  the  foothills  is  a  body  of  sedimentary 
rocks  of  Eocene  age.     These  beds  consist  of  a  coarse  sandstone  at  the 


PETROLEUM    RESOURCES   OF    CALIFORNIA,  179 

bottom  whioh,  in  somo  plaoos,  is  of  a  dark  red  color,  due  to  stains  from 
various  iron  eumpouuds.  Above  tbe  sandstone  are  found  beds  of  clay, 
volcanic  tuff,  and  eonfrlomorate.  It  is  probable  that  these  beds  repre- 
sent the  most  southerly  extension  of  the  lone  formation  and  Dickerson^ 
has  found  ^ood  Tejoii  fossils  in  tlie  sandstone  member  in  the  vicinity 
of  I\Ierced  Falls. 

These  beds  do  not  contain  any  indication  of  petroleum,  and  they 
lie  in  a  gentle  monocline,  dipping  a])out  4°  to  the  east.  It  is  i)robable 
that  they  underlie  the  greater  part  of  the  northeast  portion  of  the  San 
Joaquin  Valley. 

The  geological  conditions  of  this  region  are  distinctly  unfavorable 
for  the  production  of  petroleum.  This  is  based  on  the  following  facts: 
There  are  no  surface  indications  of  oil;  the  oil-bearing  formations, 
which  are  present  in  the  proven  areas  of  the  valley,  are  lacking  here; 
such  .sediments  as  are  present  are  not  of  a  character  to  form  oil;  there 
is  no  structure  evident  that  is  favorable  for  the  accumulation  of 
petroleum. 

From  the  above  it  is  evident  that  the  region  is  not  a  desirable  one 
in  which  to  prospect  for  oil. 

Near  Knights  Ferrv,  in  See.  18,  T.  1  S.,  R.  12  E.,  W.  H.  Clary  is 
drilling  a  well.  At  Oakdale,  in  Sec.  1,  T.  2  S.,  R.  10  E.,  the  Southern 
Oil  and  Gas  Company's  well  has  reached  a  depth  of  nearly  4000  feet. 
Showings  have  been  reported  from  this  well,  but  liave  never  been 
verified  bj-  any  representative  of  this  Bureau. 


'University  of  California.     Department  of  Geology-.     Bull.  17,  Vol.  9.     Stratigraphy 
and  Fauna  of  tlie  Tejon  Eocene  of  California.     By  Roy  E.  Dickerson,  1916. 


INDEX. 

Page 

Accumulation  of  Oil,  Areas  of 20 

Conditions  necessary  for 21 

Metiiods  of 1^ 

Tlieory  of — 1^ 

Acreage,  Total  proven • —     11 

Acknowledgments 1*^ 

Alameda  County 61 

Alpine  County *8 

Amador  County   48 

Anderson  and  Pack 61,  62,  70,     93 

Anderson.  Robt. 75,   173 

Anticlinal  Theory 14 

Arnold.  R. 61,   109 

and  Anderson,  Robt.- — 102,   175,   176 

and  Johnson.   Harry 98,  99,   167,   171,   172 

Arrovo  Grande  Oil  Field — 32,     95 

Augur,  Irving  V — 10,    131,   136,   151 

Ball,  Sidney  H 155 

Bear  Valley 52 

Bell,   H.   W 103 

Belridge  Field — ___ 32,   168 

Bitterwater  and  Peachtree  Valley,  Geology  of 78 

Bradley-San  Miguel  Oil  Company — 90 

Bradlev,  Walter  W 10 

Branner,    J.   C — 62,   63,      66 

Brea  Canyon,  Area  vicinity  of 123 

Field    — 136 

Bullis,   C.   G — ___ 10 

Burnt  Shale  areas — 22 

Butte  County,  Eastern 48 

Western    — 49 

Button   Willow   District 178 

Calaveras   County   48 

California,  Geological  facts  of  origin  and  accumulation 13-22 

Geology  and  structure  of__-- 23-34 

Index  map  of — 8 

Map  of In  Pocket 

Oil-bearing  formations  of — 23—34 

Statistics  for  1920 11 

Summar.v   of  conclusions — 11 

Theory  of  origin  and  accumulation  of  oil  in '. 13—22 

Camarillo,  Oxnard  and  El  Rio,  District 126 

Carpinteria,  Region  near-- 111 

Carrizo  Plains  and  San  Juan  Creek 98 

Geology — 100 

Oil  Wells — 100 

Chico  formation -_ 27,     28 

Chino-Corona  United  Co — 159 

Chino  Land  and  Water  Co _- 159 

Ciervo  Anticline,  Crest  and  flanks  of 75 

Clark,  Prof.  B.  L..  University  of  California 10,  30,     34 

Coalinga  District 31 

Field    -- r 171 

Coast  Ranges 23-32 

From  Pajaro  River  as  far  south  as  Santa  Maria  River 69-101 

From  San  Francisco  Bay  as  far  south  as  Pajaro  River,  Area 60-68 

Coast  area  north  of  Bay  of  San  Francisco,  Possibilities  of  oil 35-44 

From  Santa  Maria  to  Santa  Monica  Mountains 102-130 

Collom,   R.   E 10 

Colusa  County 49 

Conclusions,  General  summary  of — 11 

Conejo  Field,  Ventura  County 128 

Contra  Costa  County -_ — _— 60 

Coyote  Hills  Field 137 

Cretaceous  formations — 27 


182  INDEX. 

Page 

Cuyama  Valley,  Area  of 107 

Cymric  Oil  Co 68 

Daly,  Marcel 16 

Decius,  C.  L 10 

Del  Norte  County 44 

Desert  Region — 153—161 

Southeastern    26 

Devils  Den  Field 32,   169 

Diablo  Range  south  of  Panoche  Valley 70 

Vallecitos  District 70 

Diastrophic  theory 16 

Diatomaceous   shale — 31,     32 

Dickerson,   R.    E 56,   154,   158 

El  Dorado  County 48 

Eldridge,  G.  H.,  and  Arnold,  Ralph 67,  112,  113,  121,  131,   157 

Elk  Hills  Field — 170 

El  Rio,  Oxnard  and  Camarillo,  District  of 126 

Elsmere   Canvon  wells — 130 

English,  Walter  A 88,  89,  90,  94,  98,   112 

Eocene  formation 28 

Eureka  Wells 121 

Fairbanks,  H.  W 95,   96,   112,   149 

Ferguson,  R.  N — 10 

Folger,   A.    — 10 

Foraminifera 13 

Formations,  nonoil-bearing 26 

Oil-bearing    — 27 

Fresno  County 48,   162 

Production,    1919-1920 11 

Gas  blows 21 

Gas  pressure,  Explanation  of — 16 

Gavilan  Mountains,  Area  of 86 

Geology  and  Structure  of  California — 23-34 

Sacramento  Valley,  west  side 49 

Geological  structures  yielding  oil  in  commercial  quantities 16 

Glenn  County 49,     51 

Great  Central  Valley  of  California 24 

Hershey,  O.  H 155 

Hollister  and  Lomas  Muertas,  Area  between 69 

Hooker  Hills 56 

Huasna  District 96 

Huguenin,   E.    9,      10 

Humboldt   County   — 40 

Map  of In  Pocket 

Wells  drilled  and  results — 42 

Huntington   Beach   Field 138 

Hydrostatic  pressure — 16 

Imperial  County 148 

Map  of ^^-In  Pocket 

Wells  drilling 152 

Inglewood  Hills  to  Beverly,  Region  of 140 

International  Petroleum  Company 159 

Introduction -- 9 

Inyo  County 153,   155 

Kern   County,  eastern — 153,  155 

In  Sierras — 48 

Midway  District,  showing  accumulation 17 

Western  half 162 

Production   1919-1920 11 

Kern  River  Field 172 

Kettleman   Hills 174 

Kew,  W.  S.  W 113,  148,   151 

Kings  County 162 

Kreyenhagen  Hills  region 175 

Laguna  to  Santa  Ana  Mountains,  Across  Laguna  Hills  and  Capistrano  Valley 144 

La  Jolla,  San  Diego  County 147 

Lake  County 49-51 

Lassen  County 47 

Lautenwasser  Creek,   Structure 61 

Lawson,  A.  C 23,  60,      61 


INDEX.  183 

Page 

Lewis  Creek   — '^ 

and  peachtree  Valley,  Monterey  County 70 

Lewis,  J.  O l^ 

Lomas  Muertas  and  Hollister,  Area  between 69 

Loon  Point,  Wells  near HO 

Los  Angeles  City  Field -—   135 

Los  Angeles  County,  northeastern 153,   156 

Northwestern    — 12  8-130 

Wells  drilling 129 

Production,  1919-1920 --      H 

Southern  'and  Orange  County 131-144 

Salt   Lake   Field 17.   135 

Los   Gatos   64 

Lost   Hills  Field 32,   168 

Madera  County,  western — 162 

Mahala  Oil  and  Gas  Company 159 

Marin  County 35 

Point  Reyes  Peninsula 37 

Martinez  formation 28 

MarysviUe   Buttes 56 

McDonald,    R.    C — 10 

McKinney,  Don 10 

McKittrick  Field 167 

McLaughlin,  R.  P.,  and  Waring,  C.  A 94,  98,  100,  111,  155,  171,  172 

Madera  County,  eastern  part 48 

Mariposa  County — 48 

Mendocino  County 39 

Wells  drilled — 40 

Merced  County 162 

Midway  District,  showing  accumulation 17 

Midway-Sunset  area 32,   166 

Miocene  formation — 30 

Modoc  County — 46 

Monocline,  form  of 15 

Mono  County 153-154 

Montebello  Field 135 

Montecito,  Region  west  of 111 

Monterey  Bay,  District  bordering  on 83 

Monterey  County 31,  32,     82 

Monterey  sliale  formation — 31,     32 

Montezuma  Hills 57 

Napa  County 49,  51,  52,     56 

Nevada  County 48 

Newhall   Fields 129,   130 

Newport  District 138 

Northeastern  California  oil  possibilities 45-47 

Lava  beds  of 25 

Oak  Ridge  and  South  Mountain,  North  flank  of 117 

Oil-bearing   formations.    Description 23-34 

Cretaceous . 27 

Eocene    28 

Oligocene 29 

Miocene    -- 30 

Pliocene   32 

Oil  City  Field 2S 

Oil,  Origin  and  Accumulation 13-20 

Possibilities  Northeastern  California 45-4  7 

Possibilities,  Area  north  of  Bay  of  San  Francisco — 35-44 

Production  by  counties 11 

Surface   indications  of 21 

Summary  of  conditions  necessary  for  accumulation  in  commercial  quantities--     21 

Ojai  Valley  Field -- 32,  113 

Ojai  Valley  and  Sulpliur  Mountain 114 

Oligocene  formation 29 

Olinda  Field -- 136 

O'Neal,   Tom 10 

Orange  County,  Coastal  plain  area 134 

Laguna  to  Santa  Ana  Mountains 144 

and  Soutliern  Los  Angeles  County 131-144 

Eastern    portion    of 142 

Production  1919-1920 11 


184  '*  '  INDEX. 

Page 

Origin  and  accumulation  of  oil,  theory  of __13-20 

Oxnard,  El  Rio  and  Camarillo,  district  around 126 

Pack.  R.  W.,  and  English,  W 77,  91,  92,  157,   171,  172,   173 

Pan-American  Petroleum  Co 123 

Parkfield  District 92 

Location  of  wells  in 93 

Peachtree  Valley,  Geolog>-  of 78 

Petroleum    (see  Oil) 

Piru  Field --__32,   120 

Eureka  wells 121 

Placer  County,   Eastern 1 48 

Western   -- 49 

Pleyto  oil  district 88 

Wells  drilled  in 88 

Plumas  County 48 

Pomona  Petroleum  Company 159 

Potrero  Hills 51-52 

Production  of  oil  for  1920 11 

Proven  oil  land,  Total 11 

Prutzman,  P.  W 113,   129,   131 

Point  Arena,  Map  of In  Pocket 

Point  Reyes,  geologic  section — 37 

Report,  purpose  of 9 

Reservoirs    ^ 18,     19 

Richfield  District 136 

Rincon  Creek  and  Cajpinteria,  wells  near — 110 

Riverside  County 153,   159 

Sacramento  County 49 

Sacramento  Valley,   including  east  slope   of  Coast  Range  and   foothills   of  Sierra 
Nevada, 

Area   of -_ 49-59 

District  of  valley  floor 56-57 

East  side  and  foothills  of  Sierra  Nevada 58-59 

Western  side,  sections 53 

West  side  and  east  slope  Coast  Ranges 49-56 

West  side,  Map  of In  Pocket 

Salinas  Valley  from  Greenfield  south  to  County  line 89 

From  King  City  soutli  to  County  line.  Area  of 91 

Mouth  of,  and  district  Bay  of  Monterey 83 

Salinas  to  Greenfield,  Area  of 86 

Salt  Lake  Field I35 

Section  of 17 

San  Antonio  Hills,  Area  of 87 

San  Ardo,  Area  west  of 90 

San   Benito  County 1 69-82 

River  valley , 82 

Southwestern  portion   of 76 

and  Tres  Pines  valleys 70 

San  Bernardino  County — 156 

Mountains  lying  west  of 158 

Wells  drilling — 159 

San  Diego  and  Imperial  counties 145-152 

San  Diego  County — 145 

La  Jolla : 147 

Santa  Margarita  Valley,  along  north  side — 147 

Wells  drilled 146 

San  Fernando  Valley  district 132 

San  Francisco  County 62 

San  Gabriel  Valley 142 

San  Juan  Creek  and  Carrizo  Plains 98 

San  Joaquin  County 162 

Valley,    Region    of 162-179 

East  side  of 178 

Proven  fields,  Region  of — 164 

Tulare  Lake,  proven  fields  and  possible  accumulation 165 

Unproven  areas 173 

San  Luis  Obispo  County 94 

San  Mateo  County 62 

San  Pablo  Valley  indications . 61 

San  Pedro  Hills,  Region  of 141 

San  Pedro  and  Santa  Monica,  Region  between — ^ ^.^_,.^_„. 141 


INDEX.  185 

Page 

Santa  Ana,  upper  San  Benito  and  Tres  Pinos  valleys,  Area  of-- 70 

Santa  Barbara  County,  Coast  area  of 109 

Santa  Barbara  County 102 

Production   1019-1920 — 11 

Proven  fields  and  adjoining  areas . 102 

Santa  Maria  Field,  sliowing  accumulation 17 

Santa  Clara  Countyl 63 

Moody  Gulch — _— 30,  31,      65 

Santa  Cruz  County 66 

Santa  Fe  Springs  District 137 

Santa  I^ucia  Mountains,  Area  of 83 

Santa  Maria  Field 31-32 

Santa  Maria  River  to  Santa  Monica  Mountains,  Coast  area  from 102-130 

Santa  Monica  and  San  Pedro  region,  Between 141 

Santa   Paula   I-'ield 32,   115 

Santa  Ynez  Mountains  west  of  Santa  Barbara,  Area  of 106 

Sargent  Ranch  field —      66 

Schumacher,    \V.    E 10 

Sespe  Canyon  area 120 

Shasta  County 46 

Sliell  Co. 66,     90 

Sierra  County 48 

Sierra   Nevada   Mountains 25,     26 

Area  of — 48 

Signal  Hill  district 139 

North  to  Inglewood  Hills,  Region 140 

Simi  Valley,   Section  of 114 

Unproven  areas -- 124 

Sisar  Creek  field : 113 

Siskiyou  County — 45 

Solano  County 49,  52,  55,     57 

Sonoma    County — 36 

Evidences  of  petroleum 38 

South  Mountain  and  Oak  Ridge,  District  along  north  flank  of 117 

Staldf-r,    W -- 43 

Standard  Oil  Co 76,   106 

Stanislaus  County — 162 

State  Mining  Bureau  cited __43,  62,  64,  77,   86,  89, 

91,    94,    96,    98.    110.    Ill,    112,    113,    117,    129,    131,    146,    149,    151,    154,    171,    172 

State  Oil  and  Gas  Supervisor 11,  103,  104,  105 

Structure,   types   of — 15 

Sulpliur  Mountain  and  Ojal  Valley 114 

Summary  of  Conclusions 11 

Summary  of  conditions  necessary  for  accumulation  In  commercial  quantities 21 

Summerland  Field 109 

Region   northeast  of HI 

WelLs  in  mountains  northeast  of 110 

Surface  indications  of  oil — 21 

Sutter  County 49,     56 

Syncline,    form   of --__     15 

Tapo  Canyon  wells — 122 

Tehama  County — 49,     50 

Tejon  formation 29 

Temblor  Range,  region  of  foothills — 174 

Theories  as  to  origin  and  accumulation  of  oil 13-22 

Thoms,   C.   C 10,   170 

Tickkell,  F. 10,      96 

Topo  Ranch,  Geology  of — 81 

Wells  drilled 82 

Toro  Creek — 76 

Tnrrey  Field 121 

Tres  Pinos  and  San  Benito  valleys — 70 

Tres  Pinos,  upper  San  Benito  and  Santa  Ana  valleys.  Area  of 70 

Trinity  County 44 

Tulare  County,  eastern  part — 48 

Western  half 162 

Tulare  Lake,  Region  around — 177 

Tuolumne  County 48 

Tuscan  Oil   Company — 56 

Union  Oil  Company 123 

13—13322 


186  INDEX. 

rage 

U.  S.  Bureau  of  Mines -- 19 

U.  S.  Geological  Survey 10, 

17.  46,  56,  60,  61,  62,  63,  66,  67,  70,  75,  77,  85,  87,  89,  90,  91,  92,  93,  95,  96,  98, 

102,   104,   107,   109,  112,   113,  131,  148,   151,  155,  157,   167,   171,   172,   173,   175,  176 

University  of  California-,  Department  of  Geology 23,  56,  150,  154,  158 

Upper  San  Benito,  Tres  Pinos  and  Santa  Ana  Valleys,  Area  of-- -- 70 

Vaca   Valley   51 

Vallecitos   District -- - 70 

Vaqueros  formation 30.  31 

Ventura  County -- 32.  112 

Central  portion,  area  of  proven  fields 113 

Conejo   Field --  — -- -- 128 

Field 116 

Northern  half.  Geology  and  oil  possibilities 112 

Production,    1919-1920    11 

Santa  Monica  Mountains  district 126,  131 

Simi   Valley 114 

Sulpluir  Mountain  and  Ojai  Valley '. 114 

Waring,    C.   A -- 64,  89 

and  E.  Huguenin 155 

Watsonville   Oil   Company 66 

Western  Union  Company 106 

West   Side  field.s -_ 164 

Whittier   Field    -" 136 

i'olo  County  49,  52,  55 

Yuba  County 48,  49 


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13322 


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